CS-590 will not idle

[Dave41A]

Good afternoon:  This is my first post here at the Forestry Forum.  I'll apologize in advance for what is a long first post.  I have had a CS-590 for about 5 years.  Is has been a good saw, but hard to start when hot.  However, now it will start but not idle.  It will also not run wide-open, but instead bogs dies and dies upon squeezing the throttle.  This is actually an improvement from a few days ago, when it would not start at all. 
 
I will summarize what I have done:  fresh gas, cleaned & gapped sparkplug, checked for spark (good), removed and cleaned carburetor (including removing rubber diaphragms and probing jets with a fine wire).  While I had the carb off, I noticed that the choke linkage at full choke is supposed to also set the throttle to about one-quarter, which should stay that way until the gas lever is squeezed & released.  Mine would do this nicely off the saw (and make a nice "click" when set) but the choke lever would hit the front side of the air cleaner housing when installed on the saw—preventing it from going to full choke and not staying there (which explains the hard hot starts).  I installed a thin gasket as a spacer between the carb and this air cleaner housing which now allows the choke to apparently function properly with 1/32 inch extra room:  At full choke the throttle is "set," and at stays there when pushing the choke off.  Squeezing the gas releases the throttle back to idle.  Now, when cold,  it will fire after 1-2 pulls at full choke, and fire up in 2-3 pulls, and run at a fast idle (chain moving) while it remains at "half choke" (the throttle linkage keeps the choke from fully opening until the gas lever is squeezed, even if the choke is "off"). 
 
However, even if I allow the saw to warm for a good 30 seconds, upon squeezing the gas lever, the saw will immediately die.  If I squeeze and hold, it will die.  If I squeeze and release, it will die.  I have removed the carb screw limiters and back off the L screw as described in video posted here by Andyshine77 for the CS590.  Following another video also posted by the same person, I have backed the L screw out two full turns and the saw still will not idle.  After it dies it starts right back up again reliably and runs until I squeeze the gas lever again.
 
Like many others here, I am stuck at home with the virus measures, so taking it to a repair shop or dealer is not an option for the near future—they are all closed anyway.  The saw has maybe only a few months left on its warranty; I would like to learn how to fix it as I hope it will last me a lifetime. 
 
I cut about 3 cord a year for firewood but now have a band saw so will be cutting significantly more as I am trying to build a barn.  I am at about 1000' above sea level—it is mid 40's outside.  I had been running 90 octane, ethanol-free gas; now am on 87 regular as that's what I have right now. 
 
I have experience working on other gas-powered equipment (mostly tractors) and have been using chain saws for 25-30 years or so, but have much less experience fixing them than tractors.  I've posted this question over at my usual forum (yesterdays tractors) but have not gotten very far with the responses, as the experience base there is very different from what I see here.  I can post pictures or additional details if required.  
Thanks in advance for your help.  Any suggestions are appreciated.  Dave 

[dougand3]

Welcome. Plenty of good data in your post.
Did you change the carb diaphragms? New diaphragms are in order.
Check that muffler screen is not blocked with carbon.

[Dave41A]

Welcome. Plenty of good data in your post.
Did you change the carb diaphragms? New diaphragms are in order.
Check that muffler screen is not blocked with carbon.

The muffler screen looks clear.  I did not change the diaphragms--I put the originals back in.
I am happy to order a set if that will fix things.  As I noted, I am not experienced with chainsaw troubleshooting.  Is what I describe typical for a saw with worn-out diaphragms?
Thanks for the response & welcome.  Dave

[sawguy21]

Welcome!! Changing the diaphragms is cheap and one less thing to worry about. Also check the fuel line, it should be pliable but not spongy, and change the in tank filter.

[Dave41A]

Welcome!! Changing the diaphragms is cheap and one less thing to worry about. Also check the fuel line, it should be pliable but not spongy, and change the in tank filter.

Thank you.  I am new to chainsaw repair, and will put some diaphragms in order.  However, are diaphragms something that I can typically only expect 5 years of use from?  The fuel line seems fine--not spongy.  The in-tank filter is also the original.

[dougand3]

5 years is a long life for a diaphragm. Change the pickup (fuel filter).

[Hilltop366]

Sounds like a carb low speed circuit issue. It will be either getting too much fuel or not enough.

Did you remove the the fuel mixture screws when cleaning the carb? 

When cleaning out a carb I will take a can of wd40 and using the nozzle tube spray in each circuit and watch in the carb barrel to make sure there is flow in all the places it is suppose to and confirm that there is no blockage.

Wear eye protection.

[Dave41A]

5 years is a long life for a diaphragm. Change the pickup (fuel filter).

Thank you.  This is the kind of information I need to hear and learn.  My experience with saws to date has been either "homeowner" saws where the diaphragm outlasts the saw, or with my Father's old craftsman (1980's vintage) that still runs awesome, and I have never done anything to it!  I'll order a spare diaphragm set and keep it on hand for when the next time comes.

[Dave41A]

Sounds like a carb low speed circuit issue. It will be either getting too much fuel or not enough.

Did you remove the the fuel mixture screws when cleaning the carb?

When cleaning out a carb I will take a can of wd40 and using the nozzle tube spray in each circuit and watch in the carb barrel to make sure there is flow in all the places it is suppose to and confirm that there is no blockage.

Wear eye protection.

I did not remove these screws, and stopped loosening the L when I did as I was afraid of backing the screw out and never being able to get it back in for some unknown-to-me reason.  I take it that I can remove these screws, clean inside & blow WD-40 through as you describe, then re-assemble without difficulty?  Thank you for your response.  Dave

[Hilltop366]

Yes they can be removed, usually first I will turn them in until they lightly seat fully while counting how many turns it takes to get there, record the number of turns (eg  H=1½ or L=1¼) then remove.

Then when you put them back in screw them in until they seat again and back out the recorded number of turns.

When flushing out and checking passages put your finger over the H and L holes and put the spray tube in the holes that feed the circuit on the metering side of the carb (under the metering diaphragm) and watch for the fluid to come out in carb barrel checking to see if it comes out the holes. If any are restricted they can usually be cleaned out with a small piece of wire, I like to use brass wire from a brush or copper from a multi strand wire. then test again.

If you have new diaphragms you might as well put them in but 5 year old ones should be ok unless they had gas dry up on them and feel stiff, in a pinch I have cleaned them off before by rubbing them with my fingers and/or finger nail to "loosen" them up, check to make sure the 2 fuel pump diaphragm flaps lay down flat on the carb body too.

[Dave41A]

Yes they can be removed, usually first I will turn them in until they lightly seat fully while counting how many turns it takes to get there, record the number of turns (eg  H=1½ or L=1¼) then remove.

Then when you put them back in screw them in until they seat again and back out the recorded number of turns.

When flushing out and checking passages put your finger over the H and L holes and put the spray tube in the holes that feed the circuit on the metering side of the carb (under the metering diaphragm) and watch for the fluid to come out in carb barrel checking to see if it comes out the holes. If any are restricted they can usually be cleaned out with a small piece of wire, I like to use brass wire from a brush or copper from a multi strand wire. then test again.

If you have new diaphragms you might as well put them in but 5 year old ones should be ok unless they had gas dry up on them and feel stiff, in a pinch I have cleaned them off before by rubbing them with my fingers and/or finger nail to "loosen" them up, check to make sure the 2 fuel pump diaphragm flaps lay down flat on the carb body too.

Thank you very much for continuing to respond.  I have removed both adjustment screws and sprayed wd-40 into the screw holes as you describe.  I have also done it with the screws installed but with the metering diaphragm removed.  I can spray into the hole next to the Welch plug and into the brass plug/insert.  In all cases the WD-40 comes out all 3 idle holes/jets or the main jet, as appropriate (e.g. the right places).  I have reinstalled the carb, and began with both screws 1-1/2 turns out (Unfortunately, I did not record their initial settings as you describe).  It will fire on the first pull at full choke.  Then it will fire and run on the first or second pull with the choke in.  But as soon as I squeeze the throttle lever, it dies.  Every time.  I heave repeated this after backing out the L screw 1/4 turn at a time for 2 full additional turns (3-1/2 turns total) with no success.  New diaphragms are on order but the current ones look usable and are not stiff at all.  I can post pictures of the diaphragms but find it difficult to believe that their condition would degrade the saw's performance so much that it will not run at all.  Thanks again, Dave

[Dave41A]

Yes they can be removed, usually first I will turn them in until they lightly seat fully while counting how many turns it takes to get there, record the number of turns (eg  H=1½ or L=1¼) then remove.

Then when you put them back in screw them in until they seat again and back out the recorded number of turns.

When flushing out and checking passages put your finger over the H and L holes and put the spray tube in the holes that feed the circuit on the metering side of the carb (under the metering diaphragm) and watch for the fluid to come out in carb barrel checking to see if it comes out the holes. If any are restricted they can usually be cleaned out with a small piece of wire, I like to use brass wire from a brush or copper from a multi strand wire. then test again.

If you have new diaphragms you might as well put them in but 5 year old ones should be ok unless they had gas dry up on them and feel stiff, in a pinch I have cleaned them off before by rubbing them with my fingers and/or finger nail to "loosen" them up, check to make sure the 2 fuel pump diaphragm flaps lay down flat on the carb body too.

I will add that the idea of too much gas has also crossed my mind.  So I seated the L screw and backed it out 1/4 turn at a time.  It would fire every time, but not continue to run.  At about 1-1/4 turns out, it now fires and runs at partial throttle/half choke as I described.  But again, as soon as I touch the throttle lever, it dies.  Thank you again for your help.  Dave

[Hilltop366]

Does it run at any speed with the choke off?

I was thinking it would run at fast speed but die at low speed.

[Dave41A]

Does it run at any speed with the choke off?

I was thinking it would run at fast speed but die at low speed.

No. If I squeeze and hold the throttle, it dies.  If I squeeze and release, it dies.  Anything that disturbs the carb from a half-choke condition makes the saw stop running.  Thank you for continuing to work with me on this.  Dave

[Hilltop366]

Ok sorry about that, for some reason I was thinking it was a only dying at low speed. 

Did you check your fuel filter, with it removed you should be able to blow through where the gas line connects easily.

[Dave41A]

Ok sorry about that, for some reason I was thinking it was a only dying at low speed.

Did you check your fuel filter, with it removed you should be able to blow through where the gas line connects easily.

Yes.  If I do not loosen the fuel cap before removing the fuel line form from the carb, it will spill fuel all over the place from tank pressure pushing fuel up the hose.  I also tried running it once with the filter removed to see if that made a difference.  It did not.  
I can also blow backwards down the fuel line through the filter without difficulty.
Thank you again for continuing to respond.  This is very helpful even if it is still not running.  Dave

[Hilltop366]

Did you get the metering and pump diaphragm and gaskets back on in the correct order?

You can look up a parts diagram for the saw on line for a exploded view of the carb, there may be a serial number range specific to your saw.

 Does the needle move freely in the seat?

[Dave41A]

Did you get the metering and pump diaphragm and gaskets back on in the correct order?

You can look up a parts diagram for the saw on line for a exploded view of the carb, there may be a serial number range specific to your saw.

Does the needle move freely in the seat?

The needle does move freely in the seat.  The little spring in in place and looks to be in good condition.  
I will triple-check, but I am working from this parts diagram, and am pretty confident everything is in the right place (attempting to attach photo, link if that does not work)
Edit as of 8:46 PM:  I have verified that everything is in its place per the attached diagram.


Link deleted by Admin. as photo links not permitted

[Al_Smith]

Just a reminder of the fact every carb manufacture has a web site and in that web site lists not only IPL's but tuning tips .Such examples as why a saw bogs down on a throttle up ----just saying . ;)

[Dave41A]

Just a reminder of the fact every carb manufacture has a web site and in that web site lists not only IPL's but tuning tips .Such examples as why a saw bogs down on a throttle up ----just saying . ;)

Al:  Thank you for your response.  I have dug around a little at the walbro carburetor website.  I have not been able to find any tuning tips.  I also checked the echo-usa website with no success there either.  I also am not familiar with the abbreviation "IPL." 
If you could provide some guidance on where to look on these websites (I recognize there are limitations on posting external links), it would be appreciated.  Thank you!  Dave

[sawguy21]

IPL means iluustrated parts list.

[Dave41A]

IPL means iluustrated parts list.

Thank you!  I have seen the exploded diagrams, I am starting to wonder if the o-ring that forms the seal between the carb and the bellows that leads to the crankcase may be bad.  If there is a vacuum leak at this point, it would at least explain the inability to idle.  I had a tractor that would not idle and it was a leak on the intake side that was the culprit--it only became apparent during the high-vacuum situation during idling.  Would a thin layer of RTV or form-a-gasket like a Permatex 2B be out of order here?  I would need to be careful not to get any into the crankcase.
Visually this O-ring looks OK, but I am starting to think it is either that or the bellows themselves that is the source of the problem.
Thanks again, Dave

[Al_Smith]

In generalities when you go from idle to high speed operation if the idle jet is too lean the increase in pressure drop will suck up too much fuel from the idle circuit before the high speed kicks in.The idle jet is below the throttle butterfly and the high seed is above slightly .This seems to be more pronounced if the saw engine or whatever it is not warmed up .For example I have to partly choke my Stihl BG 85 blower for a few seconds because of this which although I should tune the carb better I just have not done so .

Actually believe it or not the idle jet will put out enough  fuel to run at speed without the aid of the high speed it just won't produce as much power ---usually .

[Dave41A]

In generalities when you go from idle to high speed operation if the idle jet is too lean the increase in pressure drop will suck up too much fuel from the idle circuit before the high speed kicks in.The idle jet is below the throttle butterfly and the high seed is above slightly .This seems to be more pronounced if the saw engine or whatever it is not warmed up .For example I have to partly choke my Stihl BG 85 blower for a few seconds because of this which although I should tune the carb better I just have not done so .

Actually believe it or not the idle jet will put out enough  fuel to run at speed without the aid of the high speed it just won't produce as much power ---usually .

Al:  Thank you.  I've been able to start and run the saw at "half choke," and have run it this way for 30 seconds or longer--as long as I don't touch the throttle.  I have done this repeatedly until the engine is good and warmed up.  However, as soon as I touch the throttle linkage, the engine dies.  If I squeeze and hold, it dies, and if I squeeze and release, it dies.  This linkage releases the choke from half-open to full-open, so for whatever reason, this saw only runs at half-choke.  I've backed out the L screw from closed to a full 3-1/2 turns open.  Below 1-1/4 turns open, it will not even run on half choke.  From 1-1/4 turns on up, it runs, but still only at half choke.  It does this with the air filter on and removed.  I am opening the screw 1/4 turn at a time.  Thanks again, Dave

[Hilltop366]

Where is your high speed (H) set?

[Dave41A]

Where is your high speed (H) set?

H is set at 1-1/2 turns open.  Thank you for your continued help.  Dave

[Al_Smith]

If this link works try this .I couldn't get into the Walbro site or just lack the patience for it .This should be the service for a Tillotson model HS which is a common carb and they all work the same ----https://tillotson.ie/wp-content/uploads/2015/07/techinfo_hs_us.pdf

[Dave41A]

If this link works try this .I couldn't get into the Walbro site or just lack the patience for it .This should be the service for a Tillotson model HS which is a common carb and they all work the same ----https://tillotson.ie/wp-content/uploads/2015/07/techinfo_hs_us.pdf

OK thank you.  The download worked.  That is very good information. 
The only thing I see in common between the "will not idle" and the "will not accelerate" (mine won't do either) is the needle valve lever setting.  I will look at this carefully--sort of like setting the float in a bowl carb.  I am thinking the metering chamber is not getting enough fuel.  I will also double-check the needle valve passage for obstructions using the WD-40 method.  I will dig around a little and see if I can find the lever setting for the Walbro HDA 268A.  Thanks again.  Dave

[Dave41A]

If this link works try this .I couldn't get into the Walbro site or just lack the patience for it .This should be the service for a Tillotson model HS which is a common carb and they all work the same ----https://tillotson.ie/wp-content/uploads/2015/07/techinfo_hs_us.pdf

I removed the lever & needle on the metering side and the inlet screen on the pump side.  I probed this hole with a fine wire and looked through and could see a pinhole of daylight.  I also blew WD-40 through it and it went through in both directions.
Based on what I read in the manual provided by Al, I was able to search for the equivalent guide from Walbro, which is their C-1022 service manual.  I was able to download a copy of this manual from an RC aircraft site.  Setting the lever on the HDA series carburetor normally requires use of the walbro 500-13 gauge, but for the HDA series, which this is, the lever is simply set flush with the flat surface of the carb.  I used a machinist rule and verified that this was correct.
I re-assembled and set the lever as described above, then installed the carburetor back on the saw.  Both L and H are set at 1-1/2 turns out, which is the starting position specified in the C-1022 manual.
I have re-assembled the saw, and taken it outside.  It will fire on the first or second pull at full choke.  I then push the choke in (e.g. half choke, throttle set), and pull again.  On the first or second pull, it will fire, run fast for 3-4 seconds, and then die.  I am not touching the throttle lever at all when doing this.  If I squeeze and release, the engine dies.
The C-1022 manual is very helpful, and explains the differences between diaphragm and bowl carburetors on page 5, which makes this more understandable to me.  However, I do not feel I am any closer to a running saw.
Thanks again to everyone who has contributed to this effort.  Dave

[Dave41A]

As an update to what is going on, I worked on the saw a few more hours this evening.  One test I did is as follows:  I removed the carburetor from the saw, and with the sparkplug out, turned the engine over by pulling the starter cord.  I felt at the end of the impulse pipe and felt no spurts of neither pressure nor vacuum from this hose.  I then removed the diaphragm from the carb, and reconnected the carb to the fuel hose and impulse pipe.  I then turned the engine over as before, while depressing the metering lever with my finger (e.g. needle valve open).  I then cranked the engine several times by hand, expecting to see fuel come from the needle valve area.  Nothing.

I then blew into the impulse pipe (hose) and air blows right through it.  I turned the engine to several positions to ensure the scavenge & exhaust ports were blocked/closed, but it made no difference.  It is as if the crankcase end of the impulse pipe/hose has broken off or become disconnected.  There is plenty of vacuum at the crankcase bellows intake, but none at the vacuum line, even if I partially cover the intake bellows with my thumb.

It will take me some time to dig into how and where the impulse line connects, but my reasoning is as follows:  When the engine is at full or half choke, there is enough vacuum in the carb barrel to pull fuel all the way from the fuel tank--through both check valves and the needle valve--despite a non-functioning fuel pump.  However, when the choke is released, this vacuum drops, and then the engine dies.

I am new to this so this is just an educated guess based on what I observe.  Is there a more reliable way to test for a functioning fuel pump?  Should I be able to blow through the impulse pipe like I describe?  This is number "8" in the attached diagram.

 

Any insight is appreciated--especially an easy (easiest) way to access the other end of the impulse hose.  Thanks for the pointers from everyone so far.  I am definitely learning about saws.  Dave

[Dave41A]

Yet another update:  I once again removed the metering diaphragm from the carburetor.  I connected a small syringe to the impulse connection on the carburetor.  I pumped the plunger of the syringe while holding the needle valve open with my finger.  Sure enough, fuel began to pool at the needle valve seat.  Repeating this test with the impulse line connected did not cause fuel to pool, even with repeated pulls of the starting cord.  So I am making progress.  Somehow this impulse line is not doing its job.  It is not plugged, so it is either broken or disconnected.  Thanks to everyone still reading.  Dave

[Hilltop366]

Sounds like you are making progress, not pumping fuel will certainly impede performance.

I always try to try to look on the bright side, just think of all the new things you have learned that you hope to never have to use again! 

[Dave41A]

Sounds like you are making progress, not pumping fuel will certainly impede performance.

I always try to try to look on the bright side, just think of all the new things you have learned that you hope to never have to use again!

Thank you for your continued interest.  I was able to remove part of the rear handle of the saw and peek in between the handle assembly and the crankcase.  Sure enough, there is the impulse hose, dangling there, connected to nothing!
I can also see the little hose nipple where it is supposed to connect.  Somehow it worked itself free.
Right now the only thing holding the two halves together is the bellows.  This is part 12 in the diagram I posted earlier.  It looks like it is a press fit into the rear handle assembly, but I am not sure.  Having never taken one of these apart before, I do not want to force it and break things.  These are not the most expensive parts on the saw, but I do not need more down-time waiting for another parts order.  I am (and have been) burning good daylight, as the saying goes.
Any insight as to how to disconnect the intake bellows from the rear handle assembly on a CS-590 is appreciated.



 
Edit, 12:30 PM:  I figured it out.  Got the bellows disconnected--there is a little metal retaining ring that keeps the bellows expanded into the rear handle assembly intake opening.  This ring slips out, then allows the rubber bellows to be collapsed down to fit through the hole.

Here is a picture after the cleaned off some of the sawdust and oil.  The impulse hose and crankcase nipple (at screwdriver tip) are both clearly visible.  The disconnected hose also probably least reduced my crankcase vacuum at idle, making it harder for the carb to provide the right mixture to the engine, anyway.  This would be true even if the carb was being supplied with fuel--which it clearly wasn't.  I'll have to see if I have a small hose clamp I can put on this line.

I have to work on a few other things for the next few hours but will get back to it this evening.  I will post back when I have a running saw.

Thanks to everyone for the help here.  Dave

[Dave41A]

As of 7:40 this evening, I have the saw back together.  It starts OK, and will idle.  I can rev it to full throttle and it runs at high speed fine as far as I can tell.  However, after releasing the throttle it drops back to idle but it only idles for maybe 7-10 seconds before quitting.  It restarts without problems. I assume this is a carburetor tuning problem or one of the other issues already identified (old diaphragms/gaskets, fuel filter, etc.).  However, any insight would be appreciated.

Thanks again.  I would not have made it this far without the insight provided here.  Dave

PS:  As an aside--either I have huge feet or the CS-590 was made for people with feet like bananas.  I cannot get my foot in the rear handle with work boots on!

[sawguy21]

 :D I hold the wrap handle in my left hand and push the saw away as I pull. The big bruisers go on the ground. Being a southpaw I developed a bad habit of holding the saw with my right and pulling with my left, I quickly learned the folly of that method, saws did not yet have chain brakes.

[Hilltop366]

Start and warm up the saw then adjust your low speed mixture and reset your idle speed to see if you can improve it.

If it smokes a bit when you restart it after stalling (no choke) it is likely too rich, turn L in a bit.
If it restarts a bit hard and may requires some choke it is likely too lean, turn l out a bit.

Turning either mixture screw effects the other a bit so it can be back and forth a few times to get it balanced out.

Be careful not to set the high speed too lean, how I set mine is when running at full throttle turn the H mixture screw out until it just starts to "4 stroke" usually it will "clean up" when the engine gets a load on it (cutting wood), if not turn the H in a tiny bit and try again. I would rather it run a bit under max and not chance over heating.

[Dave41A]

Start and warm up the saw then adjust your low speed mixture and reset your idle speed to see if you can improve it.

If it smokes a bit when you restart it after stalling (no choke) it is likely too rich, turn L in a bit.
If it restarts a bit hard and may requires some choke it is likely too lean, turn l out a bit.

Turning either mixture screw effects the other a bit so it can be back and forth a few times to get it balanced out.

Be careful not to set the high speed too lean, how I set mine is when running at full throttle turn the H mixture screw out until it just starts to "4 stroke" usually it will "clean up" when the engine gets a load on it (cutting wood), if not turn the H in a tiny bit and try again. I would rather it run a bit under max and not chance over heating.

Hilltop:  Thank you.  I'll do what you suggest.  By "tiny bit," how much of a turn do you mean?  I have been using 1/4 turns.   Thanks, Dave

[Hilltop366]

A quarter of that quarter turn, when things get close to right it does not take much.

[Dave41A]

:D I hold the wrap handle in my left hand and push the saw away as I pull. The big bruisers go on the ground. Being a southpaw I developed a bad habit of holding the saw with my right and pulling with my left, I quickly learned the folly of that method, saws did not yet have chain brakes.

Thank you.  Good suggestion.   This is definitely easier.  Dave

[Dave41A]

A quarter of that quarter turn, when things get close to right it does not take much.

Thank you.  I started with "L" at 1-1/2 turns open per the manual, and slowly crept all the way up to 2-1/4 turns open.  There does not seem to be any effect on performance.  I can rev the saw to full throttle, release, and let it idle.  It idles for 12-13 seconds every time, then quits.  The idle speed seems to slowly creep up during the 12-13 seconds, and peaks just before it quits.  I am thinking this is still a fuel delivery problem.  Maybe a pinhole in the impulse tube or a pump check valve leaking prevents fuel from pumping at idle, or even a pinhole in the fuel line allowing the pump to suck air.  Any thoughts appreciated.  Thanks again, Dave

[donbj]

If it revs up before dieing when idling that's for sure it's running out of fuel in that circuit. It's slowly leaning out and quitting. Something going on in that circuit for sure.

[Air Lad]

Would definately put the L adjustment back to 1 1/2 -1 3/4 turns out to begin diagnose.Still could be air leak,seals ?

[brewdog]

Just had about the same with 61 huskie,had 3 different carbs on it /that wasnt the prob. couldnt get it to run past idle new gas line all is fine.

[Dave41A]

Donbj, Airlad, Brewdog:  Thank you. I have some parts on order.  I am going to start with new gaskets in the carb, then move to new fuel line, filter, and impulse line.  The saw obviously works, but one or all of these components is not up to full performance.  I am guessing the impulse line is the main problem, but the others are probably contributing, too.  As a whole, they add up and slowly starve the carb of fuel.

[Air Lad]

At the end of the day,if you go this way 
you know that once you solve the problem
all the other perishables have been updated to new and you 
should get good service from the machine for
years to come.
It's my way of doing it

[kenskip1]

David, Try this trick.On the end of the impulse line that is coming from the crankcase,put a dab of grease on the line. Just enough to cover the end of the tube.Now give the rope a few pulls with the spark plug installed.. The grease  should be drawn into the crankcase.From your well detailed analysis, I will make an assessment and say that the fuel pump diaphragm is beginning to stiffen and not pulling the gas in at lower RPM. Best of luck, Ken

[Dave41A]

At the end of the day,if you go this way
you know that once you solve the problem
all the other perishables have been updated to new and you
should get good service from the machine for
years to come.
It's my way of doing it

Thank you.  Getting a sense of what is "perishable" on these saws and in need of periodic replacement is a big part of what I am learning.  I have the fuel system from tank to carb on order, as well as a new o-ring for the fuel cap (which is almost impossible to turn now).  All good experience.  It will be 10 days before anything arrives, so now I just need to be patient.
Thanks again, Dave
PS:  The ship I was on at the time pulled into Sydney, Melborne, and Hobart back in '95-'96.  I went to see the blue mountains when ashore.  Is this anywhere near where you are?

[Air Lad]

No Dave. Sunny QLD. To the north
Cheers

[Dave41A]

Update as of 27 April 2020:  The carb kit shipped separately from the rest and arrived.  I installed new pump gaskets, new diaphragm and diaphragm gasket, new needle valve, lever and pivot, removed Welch plug, cleaned idle jets, and replaced with new Welch plug.  Adjusted needle valve lever per Walbro carb manual--flush with carb body gasket surface.

Saw starts & runs at full throttle, but when releasing throttle it will drop to idle and now only run for 7 seconds before quitting.  Adjusting low idle up and down 1/2 turn makes no effect. 

I did the grease check at the impulse line and it generates good pulses of vacuum and pressure.

New impulse hose, fuel filter, fuel line, grommet, o-ring, etc are all on backorder and are at least 10 days out.

Thanks for all the feedback so far.  Still scratching my head on this one.  Dave

[Nolan1030]

Have you done a compression check on this saw? If you have cylinder damage this would cause low speed issues. I work on two stroke outboards for a living and we always start with a compression check. A saw(or any motor) with low compression will have trouble pulling fuel at lower speeds.

[samandothers]

Dave41A  I appreciate your stick-to-it-ness!  You will wrestle this down with the help of so many here.

Nolan1030  Welcome to the forum!

[Dave41A]

Have you done a compression check on this saw? If you have cylinder damage this would cause low speed issues. I work on two stroke outboards for a living and we always start with a compression check. A saw(or any motor) with low compression will have trouble pulling fuel at lower speeds.

Nolan:  Thanks for writing back.  I have not done a compression check, but it seems to have good compression when starting it.  I use the decompression button most times.  I can pull it under full compression, but it is noticeably more difficult.  Not scientific, but I don't have a gauge available to put on it.  Is there anything else I can do instead?  Thanks again, Dave

[Dave41A]

As a follow-up to anyone still reading this post, the long back-ordered parts finally arrived, and I installed them.  I have a new fuel filter, a new in-tank fuel line, a new fuel tank grommet, a new fuel elbow, a new fuel elbow to carburetor line, a new impulse line, and new fuel tank filler cap o-ring.  I changed the O-ring first, but then changed parts one system at a time to see if it made any difference.  In order:
1) New impulse line from crankcase to carburetor--no effect
2) New fuel filter--no effect
3) New fuel lines & grommet--no effect

So, after waiting a month, I have made no progress.  The saw starts reliably, and I can warm it up by running it at full throttle.  However, it will only idle for 7-8 seconds when the throttle is released.  A re-start and it does the exact same thing.  I can even count the seconds for it to die when releasing the throttle--always 7 to 8.

I had previously done a complete carb rebuild with a carb kit and it did not make any difference, either.

Any insight is appreciated.  Thanks, Dave

[samandothers]

Not cool.  Sorry it did not do the trick.  

[kenskip1]

David, From what I hear it sounds like at idle the crankcase is pooling with gas.Simply gas is flooding the engine out. At higher speeds this is not an issue as the mix is being drawn into the cylinder. But at idle in your case the mix is forming a puddle in the crankcase instead of going into the cylinder.This is just a theory so all you experts back off.Anyway David I would do a pressure check on the crankcase and see if you are able to locate this anomaly.Ken

[Dave41A]

David, From what I hear it sounds like at idle the crankcase is pooling with gas.Simply gas is flooding the engine out. At higher speeds this is not an issue as the mix is being drawn into the cylinder. But at idle in your case the mix is forming a puddle in the crankcase instead of going into the cylinder.This is just a theory so all you experts back off.Anyway David I would do a pressure check on the crankcase and see if you are able to locate this anomaly.Ken

I agree with you that this is a fuel problem and the crankcase pressure has something to do with it.  This all began when the impulse hose somehow got disconnected from the crankcase in the first place.  It is possible something got sucked in there and caused some damage, or simply plugged something.  Before the carb rebuild I did adjust the needle lever a little to keep more fuel in the diaphragm.  This got the idle up to maybe 11 seconds or so.  So for whatever reason it is not pumping gas at idle.
Is there any experiment or test I can do easily to check this?  I am running out of options, I am really hoping that Nolan is wrong.  Nothing against Nolan, but I really hope I do not have cylinder damage.
Thanks for writing back.  Dave

[Greenerpastures]

Take off muffler and look what the cylinder and piston look like.
You may have low compression, and getting the saw to start by
having way too much fuel going in, which will still be going in
when the saw starts, this will be masked somewhat at high rpm
but at idle will flood the saw.

When the saw was running with the impulse line off, maybe
damage was caused, you won't know unless you look into the
cylinder or as others said do a vacuum and pressure test.

When you have the muffler off you could modify it if you like.

Hope am wrong too, and it's something simple, my mind reflects
 back to your mention of throttle and choke linkage settings, go
there again, disconnect the choke to ensure it's not still on,
check the throttle body closes and opens in full, that it's not closed
too much at idle, the linkage should have been right from new, so
what knocked it off, and what knocked the impulse line off.

[Dave41A]

Take off muffler and look what the cylinder and piston look like.
You may have low compression, and getting the saw to start by
having way too much fuel going in, which will still be going in
when the saw starts, this will be masked somewhat at high rpm
but at idle will flood the saw.

When the saw was running with the impulse line off, maybe
damage was caused, you won't know unless you look into the
cylinder or as others said do a vacuum and pressure test.

When you have the muffler off you could modify it if you like.

Hope am wrong too, and it's something simple, my mind reflects
back to your mention of throttle and choke linkage settings, go
there again, disconnect the choke to ensure it's not still on,
check the throttle body closes and opens in full, that it's not closed
too much at idle, the linkage should have been right from new, so
what knocked it off, and what knocked the impulse line off.

OK, Muffler is off.  I am assuming what I see here is not good.  There is a clear bright spot worn on the side of the piston, extending from the rings down the skirt about half way, maybe more. It is hard to see in there, but it looks like the far side (intake side) of the cylinder is similar.

 

[ladylake]

  May as well pull the cylinder off and see .  Steve

[Real1shepherd]

You should buy a compression tester...they're not that expensive. My guess from the last pic and all that's been written is your compression is low due to cylinder/piston transfer damage. If your saw ran too lean at some point, the damage you see could easily have happened.

It's possible your cylinder could be cleaned with acid to get rid of the aluminum tranfers and you just replace the piston/ring.

Kevin

[lxskllr]

Before getting too carried away with it, it might be worth considering a new saw. It costs $400 new. If you're getting into replacing pistons/cylinders that's gonna start racking up the dollars. A compression tester would be generally useful, so personally I'd start with that, then consider where to go from there.

[Dave41A]

Thanks to everyone who has responded.  The saw has a "Dec 2015" sticker on it...I am going to call the local Echo dealer/repair and see if they will agree to take it under warranty.  I bought this saw, which for me was a big step up in quality and price from the "homeowner" saws I had been using, because of the warranty and (when that expired) the ability to change the piston separate from the crankcase, as wiped cylinders/pistons was what had doomed the cheaper saws.  I have done business with this dealer before, and hopefully the fact that I had put a carb kit in it and replaced the fuel and impulse hoses won't invalidate the warranty.  They are apparently closed today (Memorial day and/or local COVID-19 restrictions).

If that fails then I will look into replacing the piston ($30 or so), and cleaning up the cylinder to see if it can be salvaged.

Thanks also for the suggestion on "too lean."  The carb had had the limiter caps on it, and I had not touched their adjustment, so it must have come this way from the factory.  I am guessing blow-by while cutting over-pressurized the crankcase and blew the impulse hose off. 

Thanks again to everyone for their patience while walking me though the troubleshooting.  This was my first in-depth work on a 2-cycle, and learning their ins-and-outs relative to their 4-stroke cousins has been educational.  Dave

[Greenerpastures]

Hi Dave41A, sorry to see the damage to the cylinder, that impulse line being off was a big problem. not sufficient fuel getting to the engine,
But in all honesty unless you knew what to listen for and not run the saw as soon as you noticed it was off it's tune, enough said.

But, you don't need a new saw, you have put a lot of new parts on,
Lines carb etc, I would take the cylinder off, it may well clean up,
and all you will need is a piston, rings, ORIGINAL snap rings to hold
the piston pin in, and a base gasket, still way cheaper than buying a saw,
you could do all this yourself, and people on here will be able to help
with advise re running it up, it may not end up perfect, but it will be
so close it won't matter, and will cut plenty, it could be replaced and
kept as a stand by if the need ever arises, or you could sell it and
upgrade with a clear conscience.

[Dave41A]

Hi Dave41A, sorry to see the damage to the cylinder, that impulse line being off was a big problem. not sufficient fuel getting to the engine,
But in all honesty unless you knew what to listen for and not run the saw as soon as you noticed it was off it's tune, enough said.

Greenerpastures:  Thanks.  With the impulse line off, it would not run at all--neither idle nor full throttle.  I am thinking the only sound it must have made when that line came off was the sound of a saw suddenly quitting.  Since then, I could only get it to briefly run at half choke, and I certainly wasn't cutting any wood with it that way.  It is possible that I did the piston damage myself while attempting to get the saw to run with the impulse line off.  I certainly pulled the starter cord enough times.  But I certainly wasn't operating it.
I'll see what the dealer has to say about warranty work and if the answer is "no," then I'll proceed with the new piston and cylinder salvage attempt.  I'll be sure to post pictures of what I find if I go that route.  However, if the dealer will cover the work and parts, then I'll happily agree to what will be an essentially all-new saw just shy of its 5-year old mark.  Either way, I'll post here for advice on tuning the carb, as it is now apparent to me what damage "too lean" can do. 
Hopefully I'll have an answer tomorrow from the dealer.  Thanks again, Dave.

[Greenerpastures]

I agree, doesn't take much to damage them when running lean
or dry as you tried to get fuel through the cab. I always put in an old plug
when engines are acting up at startup, take it out after a few pulls
to see if fuel is present, if not, I go no further until I find out why,
no fuel = no lubrication in out 2t engine.

Fuel air and spark, if you don't have them all, it's not happening.

Hope you get that saw back to life.

[Greenerpastures]

Before getting too carried away with it, it might be worth considering a new saw. It costs $400 new. If you're getting into replacing pistons/cylinders that's gonna start racking up the dollars. A compression tester would be generally useful, so personally I'd start with that, then consider where to go from there.

That's not a bad price, €739.00 here, never looked for a cheaper price as I can get a cs620 for the same money.

[Dave41A]

For the benefit of anyone still reading, the service department got back to me yesterday and today.  They are claiming the saw is "beyond repair" and is not covered by warranty.  I asked them to write the reason why they came to this conclusion on the receipt when I come to pick it up.  I'll post back when I get their reasons, but the explanation they gave me on the phone ("you had bad gas. when we opened the fuel tank it smelled horrible") is not encouraging.  This is too bad as one reason I got the saw was the 5-year warranty.  I bought it new in August of '16--less than 4 years ago.

[kenskip1]

Dave, I would challenge there decision.As long as it was fresh mix you should not have had a problem. This is simply a way to get them off the hook.Who made the decision? Some young person with less than a years experience? It all comes down to the mighty dollar. Personally I would attempt to make the repair myself on the other hand if your friendly dealer is a smart ass I would unload both barrels on him. Threaten him that you will call the regional office.Sometimes the squeaky wheel gets the grease.I have been following this post from the beginning, Ken

[Dave41A]

Dave, I would challenge there decision.As long as it was fresh mix you should not have had a problem. This is simply a way to get them off the hook.Who made the decision? Some young person with less than a years experience? It all comes down to the mighty dollar. Personally I would attempt to make the repair myself on the other hand if your friendly dealer is a smart ass I would unload both barrels on him. Threaten him that you will call the regional office.Sometimes the squeaky wheel gets the grease.I have been following this post from the beginning, Ken

Thanks.  I appreciate the continued interest.  They had originally called me two days ago with an estimate of $350 to $360 for repair.  I only paid $360 for the saw when new.  This was on Tuesday, 6/16/2020, and they made the claim of "bad gas."  I asked "How did you reach this conclusion?"  Their explanation "When the mechanic opened the fuel tank, it smelled horrible."  I then clarified that it could not be bad gas, and that they should double-check with the mechanic, who must be mistaken.  They called me back the next morning and told me "it cannot be repaired here, by us."  They still insisted that it was not covered by warranty, but declined to identify a reason, or point out what I had done wrong.  So this morning I went in to pick it up.  The service desk reverted to their "bad gas" explanation.  I had them write this on the receipt.  They wanted to charge me $22.50 for having the mechanic look at it, but I declined to pay.  They didn't push the point, and I took the saw and went home.  
I am going to write to ECHO directly.  I'll post later with how that went.  For anyone in the Erie, PA area, please beware of the service desk at the local "signature elite" ECHO dealer.  I could not be more dissatisfied.  Dave

[Real1shepherd]

IPL=illustrated parts listing. Google is your friend. In almost all saws, unless they are rare/oddball, an IPL can be found for your model.

Sorry, just realized I answered a question on the first page.:

Kevin

[Dave41A]

IPL=illustrated parts listing. Google is your friend. In almost all saws, unless they are rare/oddball, an IPL can be found for your model.

Sorry, just realized I answered a question on the first page.:

Kevin

No problem.  For what it is worth, Google took me as far as "abbreviations.com," which lists 46 different meanings for "IPL," ranging from "Internet Public Library" to "Intellectual Property Law" to "Intense Pulsed Light."  However, "Illustrated Parts list" is not there, but neither is "India Pale Lager," which is what I am thinking about right now.  Dave

[Hilltop366]

I have had the shoe on the other foot having been a saw, motorcycle, atv and personal watercraft dealer 30 years ago. The dealer can be in a tough spot between the manufacture/distributor and the end user. They have no way to know what has happened to a saw at the manufacture or after it left the shop with the customer and it is sometimes difficult to pinpoint a cause without spending lots of time, if they smell rotten gas that is going to be their first assumption.

As far as the pulse line falling of it is hard to know if it came off all at once or stayed on the end of the fitting giving you enough fuel to run but not enough to have the proper amount and then came off when you were working on it or just cane off when you were working on it.

If no joy with the warranty department at ECHO and you are inclined to do a bit more work you could remove the cylinder (if the repair shop did not) and see what it really needs to get the saw going again. If you are confident that the pulse line was the cause of the piston fail and you can get by with cleaning up the cylinder and buying a new piston, rings, w/p clips and gasket you could be on your way to sawing again. It would be up to you to decide if it will be good money after bad.

[Real1shepherd]

IPL=illustrated parts listing. Google is your friend. In almost all saws, unless they are rare/oddball, an IPL can be found for your model.

Sorry, just realized I answered a question on the first page.:

Kevin

No problem.  For what it is worth, Google took me as far as "abbreviations.com," which lists 46 different meanings for "IPL," ranging from "Internet Public Library" to "Intellectual Property Law" to "Intense Pulsed Light."  However, "Illustrated Parts list" is not there, but neither is "India Pale Lager," which is what I am thinking about right now.  Dave

Well, I got this far, but you need your serial# to go further:
https://www.partstree.com/models/cs-590-echo-chainsaw-parts/

Kevin

[Dave41A]

I have had the shoe on the other foot having been a saw, motorcycle, atv and personal watercraft dealer 30 years ago. The dealer can be in a tough spot between the manufacture/distributor and the end user. They have no way to know what has happened to a saw at the manufacture or after it left the shop with the customer and it is sometimes difficult to pinpoint a cause without spending lots of time, if they smell rotten gas that is going to be their first assumption.

As far as the pulse line falling of it is hard to know if it came off all at once or stayed on the end of the fitting giving you enough fuel to run but not enough to have the proper amount and then came off when you were working on it or just cane off when you were working on it.

If no joy with the warranty department at ECHO and you are inclined to do a bit more work you could remove the cylinder (if the repair shop did not) and see what it really needs to get the saw going again. If you are confident that the pulse line was the cause of the piston fail and you can get by with cleaning up the cylinder and buying a new piston, rings, w/p clips and gasket you could be on your way to sawing again. It would be up to you to decide if it will be good money after bad.

Hilltop:  Thanks.  I did explain what happened when I took it in--including all the work I had done (fuel and impulse lines, filter, carb kit)--but the fellow behind the counter didn't strike me as the sharpest tooth on the chain.  His notes on the service order invoice are crude at best.  I can understand the assumption that it was bad gas, but after I explained things a second time over the phone, they changed their story--and then back again the next day. I am sure you never treated a customer this way.
I will respectfully disagree that the mechanic has no way of knowing what has happened to a saw.  They could have asked me, the owner. To make an assumption based on one thing (and erroneously at that--I had just put fresh gas in it!) and then attempt to hit the customer with a $350 bill rather than spend the time to properly diagnose the true cause of the problem is shoddy work at best, and unscrupulous business.  Even if the repair was outside of the warranty period, I would expect that for the period of skilled labor I was billed for that the mechanic would do more than sniff the fuel tank.  Since you were a dealer, I am sure you experienced some customers abuse this--lying to the mechanic when in reality they had really mis-used the saw--but I am not some other customer.  I am not saying my trouble-shooting and mechanical skills are perfect--this certainly had me stumped for several days.  But I will state that I was honest with them about what I had done, up-front.  There is a difference between a mechanic saying "in my opinion you damaged the saw by repeatedly trying to start it with the impulse line off" and one who makes stuff up or changes stories.  I'll accept bad news as long as it is honest bad news. 
Regarding the pulse line, I was able to remove the air filter and peer down the small gap between the handle assembly and crankcase.  I could see the impulse line dangling there.  This was before I disassembled the saw further, so I can assure you it did not come apart when I was working on it.
I am reaching out to ECHO USA to see if they can remedy this.  Sorry if any of this comes across as strong, but I haven't found that "IPL" yet (second definition from earlier today), which I clearly need.  Best regards, Dave

[Dave41A]

IPL=illustrated parts listing. Google is your friend. In almost all saws, unless they are rare/oddball, an IPL can be found for your model.

Sorry, just realized I answered a question on the first page.:

Kevin

No problem.  For what it is worth, Google took me as far as "abbreviations.com," which lists 46 different meanings for "IPL," ranging from "Internet Public Library" to "Intellectual Property Law" to "Intense Pulsed Light."  However, "Illustrated Parts list" is not there, but neither is "India Pale Lager," which is what I am thinking about right now.  Dave

Well, I got this far, but you need your serial# to go further:
https://www.partstree.com/models/cs-590-echo-chainsaw-parts/

Kevin

Kevin: Thank you.  I worked through "Jack's small engines" website and ordered the fuel system components that I needed (fuel lines, filter, carb kit, etc.) on a similar "illustrated Part List."  This was before I had looked in the muffler and found the damage.  I have ordered from partstree before (for other projects, years ago), and will typically shop around from the various sources to find the best price.  However, I had always called the diagrams "exploded parts diagrams" and had never used nor heard the "IPL" abbreviation until this episode.  You learn something every day.  Thanks again and Happy Summer. Dave

[ladylake]

 
 A new piston is $56 at sepw, most likely the cylinder can be saved.  If Echo wont help I'd just put in a new piston.  You can get aftermarket ones for $30 but I'd go OEM.   Steve

[Dave41A]

Echo emailed back:

"Thank you for taking the time to email ECHO Incorporated! Due to COVID-19 prevention measures taken by ECHO, we are temporarily reducing our business operations. We apologize for the delay in answering to your email. Thank you for your patience during this time.
 
My apologies on the performance of the dealer. Unfortunately, Echo does not do returns, as we do not sell directly. Nevertheless, please attach a copy of the receipt. There are two options, you can take the unit back to that dealer, and I can forward the case to the servicing manager in that area, or you can take the unit to a different dealer for a second warranty opinion.
 
 
If you have any other questions, please update this incident and we will be happy to assist you. Our representatives are available Monday through Friday 8:00 AM to 4:30 PM (CST).

Sincerely,
Natalie
ECHO Customer Support Department
"

I will have to find a second dealer with a service department.  Not looking forward to that.

[Tacotodd]

I know EXACTLY how you feel. 

[Real1shepherd]

IPL=illustrated parts listing. Google is your friend. In almost all saws, unless they are rare/oddball, an IPL can be found for your model.

Sorry, just realized I answered a question on the first page.:

Kevin

No problem.  For what it is worth, Google took me as far as "abbreviations.com," which lists 46 different meanings for "IPL," ranging from "Internet Public Library" to "Intellectual Property Law" to "Intense Pulsed Light."  However, "Illustrated Parts list" is not there, but neither is "India Pale Lager," which is what I am thinking about right now.  Dave

Well, I got this far, but you need your serial# to go further:
https://www.partstree.com/models/cs-590-echo-chainsaw-parts/

Kevin

Kevin: Thank you.  I worked through "Jack's small engines" website and ordered the fuel system components that I needed (fuel lines, filter, carb kit, etc.) on a similar "illustrated Part List."  This was before I had looked in the muffler and found the damage.  I have ordered from partstree before (for other projects, years ago), and will typically shop around from the various sources to find the best price.  However, I had always called the diagrams "exploded parts diagrams" and had never used nor heard the "IPL" abbreviation until this episode.  You learn something every day.  Thanks again and Happy Summer. Dave

I joined some chainsaw forums in the early 2000's. IPL was a term the guys were throwing around. I'd never heard of it abbreviated like that either back then.

In vintage electronics(which I collect), there's a place called Hifi Engine and they have most Owner's Manuals and often Service Manuals for just about everything. I wish chainsaw data bases were that organized. Acres tried to do that and more but never finished.....there's a story there, but I don't know it.

Heck, back in the day there were even chainsaw magazines and I had no idea or I would have been an addict....loll!

Kevin

[Tacotodd]

Shep, you're probably not out of luck as far as chainsaw mags. Google Chainsaw Age and you should be able to see how to get some of the mags. I'm not sure how you'll do as far as electronic media goes. HolmenTree talked about it some in one of his threads or responses, I just don't know or remember which it was. 

[Air Lad]

Echo emailed back:

"Thank you for taking the time to email ECHO Incorporated! Due to COVID-19 prevention measures taken by ECHO, we are temporarily reducing our business operations. We apologize for the delay in answering to your email. Thank you for your patience during this time.

My apologies on the performance of the dealer. Unfortunately, Echo does not do returns, as we do not sell directly. Nevertheless, please attach a copy of the receipt. There are two options, you can take the unit back to that dealer, and I can forward the case to the servicing manager in that area, or you can take the unit to a different dealer for a second warranty opinion.


If you have any other questions, please update this incident and we will be happy to assist you. Our representatives are available Monday through Friday 8:00 AM to 4:30 PM (CST).

Sincerely,
Natalie
ECHO Customer Support Department
"

I will have to find a second dealer with a service department.  Not looking forward to that.

Well it's something I suppose. The first option could work if the area manager hears your side. My experience with the area managers (non related products) have been positive as a result of displaying 1. honesty 2. non confrontational dialogue. and 3. a genuine inidication of foward use and support of the brand. They want repeat customers , every successful buisness does. My $00.02 worth 

[Ianab]

Yeah, it's considerably better than "get bent"  ;)

"Get a 2nd opinion", or "Escalate it to someone higher up the chain" at least opens up some options to resolve things. 

Like Air lad says, explore those options in a non-confrontational way, especially if you go with the other dealer. They didn't sell the problem, but they might be able to fix it for you if you come across as the reasonable type.  

[Dave41A]

Just as an update for anyone still following this or perhaps reading it in the future, I took it to a 2nd dealer today.  This dealer was very different from the first.  The first was in an urban setting and mostly sold lawnmowers and weed-wackers.  This other one was out in the country--a sideline of a dairy operation and also fixed tractors.  Inside I met a man who could have been Wilford Brimley's twin brother.  After talking to him, he took me back through the shop--past a lathe and a couple of mills, a tractor split in half, and probably half a dozen snowmobiles and ATV's in various states of disassembly to meet 'Mike," who was the chainsaw guy.  Mike was out mowing but stopped that and came in to see me.  We talked, and I told him the "bad gas" story.  He shook his head and said "That's mostly used as an excuse not to work on things.  Even if you mixed 60:1 you'd have to run a long time on the wrong mix to cause damage.  If it's scored by the exhaust port, that's usually caused by heat, which means it's running too lean.  With the impulse line off, it likely sucked air in the crankcase and made it run lean & hot."  He told me that Echo was pretty good to them on warranty issues, but that he would still have to check with them to see what they wanted to do, which could be anything from a top-end rebuild (piston & cylinder) to a complete re-engine, to a whole new saw. 

So, I do not have a running saw yet, but at least have it in the hands of someone I am confident in.  It will be a couple of days yet before I find out, but at this point, even if he told me it wasn't covered, I would still be happy as at least I had a chance to talk to a mechanic who gave me a straight line and not someone blowing smoke.

[Real1shepherd]

Yeah, well you knew that original 'mechanic' was blowing smoke. Try to stay with dealers that really work on saws and not just warranty replace them. They know the in & outs and the issues from factory.

Sounds like you're headed in the right direction now and it's up to Echo.

Kevin

[kenskip1]

Dave,Have you heard anything from Echo regarding your saw? I am hoping that they would repair or replace the saw. Ken

[Dave41A]

Dave,Have you heard anything from Echo regarding your saw? I am hoping that they would repair or replace the saw. Ken

Thanks for the patience.  I called the dealer/repair place back, and they updated me on what is going on.  They checked compression, impulse, and crankcase vacuum, and all three check out properly per ECHO specs.  I spoke directly with the mechanic, and he said compression was at 160 psi.  The minimum allowed is 125.  He said he spoke with an ECHO service rep who said the apparent scoring on the piston was due to "carbon," and that as long as the saw otherwise checked out, then it was O.K. as it was (I'll be honest--this part surprised me).
However, the mechanic also had the same "idle for 7-10 seconds, then stall" problem I have.  He checked out the carburetor and everything looked fine.  His thinking is that the carburetor diaphragm is too stiff, and that the saw is not getting enough gas at idle to keep itself running.  I am not so sure about this, as I had just put a new Walbro OEM carb kit in it, but he is a more experienced mechanic than I.  Everything else about the carburetor checked out--needle & Hi/Lo settings--so I guess I re-built it properly.
He said his next step after a new carb kit came in would be to check if that fixed things.  If not, the next step would be to swap out entire carburetors with another known, working saw and see of that made a difference.  I'm not a fan of "R&R mechanics" (remove & replace parts until the thing starts working again), but apparently there are not many alternatives here.
So the good news is they are still working on it.  The bad news is...they are still working on it.  But at least they are not pushing it back at me and saying "bad gas."  So I'll take a little trial-and-error repair work if it means a working saw.  At least with both an experienced mechanic and ECHO both stumped, I don't feel so bad about not figuring it out!
For what it's worth, I would be surprised if an engine with that level of scoring would run properly.  A 4-stroke with that kind of damage would need a cylinder re-hone & re-ring at a minimum, and the "carbon" explanation sounds like "bad gas's" first cousin.  My guess is the compression test is a "false positive," and that blow-by or some other factor is ruining impulse at idle.  But, it's not my call.  The mechanic did not say for certain, but I am thinking that by now, ECHO should be footing the bill for the repair.  But I won't know until I get the saw back.
Thanks for the continued interest. Hopefully this has a happy ending.
Dave

[kenskip1]

Dave,Well it has now been a month.Have you herd anything from Echo? I would have thought that they would have been in contact with you buy now.I don't have the patients that you have.Anyway just checking in. Hopefully this will have a  good outcome.However it appears as if you are now placed on the dreaded "back burner".Keep us posted, Ken

[Dave41A]

Dave,Well it has now been a month.Have you herd anything from Echo? I would have thought that they would have been in contact with you buy now.I don't have the patients that you have.Anyway just checking in. Hopefully this will have a  good outcome.However it appears as if you are now placed on the dreaded "back burner".Keep us posted, Ken

I called back today, and the mechanic is still working on it.  He says there is something weird with the carburetor which is causing the saw to run beautifully, then die after a few seconds.  Adjustments of the needle made no effect--and he cannot figure out what it is.
Apparently the saw is not registered with Echo.  I am pretty sure I did this when I bought it, but it is possible that I did not.  I still have the receipt and provided that to the mechanic to allow him to hopefully process this as a warranty claim.  Yes, it did seem like I ended up on the back burner, but that is at least an improvement over the treatment I had before!  Thanks for the continued interest.  Dave

[Dave41A]

Dave,Well it has now been a month.Have you herd anything from Echo? I would have thought that they would have been in contact with you buy now.I don't have the patients that you have.Anyway just checking in. Hopefully this will have a  good outcome.However it appears as if you are now placed on the dreaded "back burner".Keep us posted, Ken

I called back today, and the mechanic is still working on it.  He says there is something weird with the carburetor which is causing the saw to run beautifully, then die after a few seconds.  Adjustments of the needle made no effect--and he cannot figure out what it is.
Apparently the saw is not registered with Echo.  I am pretty sure I did this when I bought it, but it is possible that I did not.  I still have the receipt and provided that to the mechanic to allow him to hopefully process this as a warranty claim.  Yes, it did seem like I ended up on the back burner, but that is at least an improvement over the treatment I had before!  Thanks for the continued interest.  Dave

So....the update that a few people have been waiting for.  The mechanic called back today, having got through to ECHO.  The story is apparently there is some internal diaphragm inside the carburetor that is out of place, resulting in the saw not running properly.  This internal diaphragm in non-repairable, so the saw needs a new carburetor.  The price tag is $100.  NOT covered by warranty as it is not a "manufacturing defect." I told him I would call him back.  
The carburetor is a WALBRO HDA-268A.  That price seems like a fair price for that part.  However, I am not 100% convinced that is really the problem.  I do trust this mechanic more than the "bad gas" guys, but don't want to spend $100 to then be told "Ooops, guess that wasn't it."
Any insight as to how to proceed?  Thanks for the continued interest over the past months.  Dave

[Dave41A]

Dave,Well it has now been a month.Have you herd anything from Echo? I would have thought that they would have been in contact with you buy now.I don't have the patients that you have.Anyway just checking in. Hopefully this will have a  good outcome.However it appears as if you are now placed on the dreaded "back burner".Keep us posted, Ken

I called back today, and the mechanic is still working on it.  He says there is something weird with the carburetor which is causing the saw to run beautifully, then die after a few seconds.  Adjustments of the needle made no effect--and he cannot figure out what it is.
Apparently the saw is not registered with Echo.  I am pretty sure I did this when I bought it, but it is possible that I did not.  I still have the receipt and provided that to the mechanic to allow him to hopefully process this as a warranty claim.  Yes, it did seem like I ended up on the back burner, but that is at least an improvement over the treatment I had before!  Thanks for the continued interest.  Dave

So....the update that a few people have been waiting for.  The mechanic called back today, having got through to ECHO.  The story is apparently there is some internal diaphragm inside the carburetor that is out of place, resulting in the saw not running properly.  This internal diaphragm in non-repairable, so the saw needs a new carburetor.  The price tag is $100.  NOT covered by warranty as it is not a "manufacturing defect." I told him I would call him back.  
The carburetor is a WALBRO HDA-268A.  That price seems like a fair price for that part.  However, I am not 100% convinced that is really the problem.  I do trust this mechanic more than the "bad gas" guys, but don't want to spend $100 to then be told "Ooops, guess that wasn't it."
Any insight as to how to proceed?  Thanks for the continued interest over the past months.  Dave

Also:  I found this discussion at another website, and thought it sounded familiar (advice on tuning carburetor):
"
....get it started on 3/4, then adjust idle speed throttle screw for steady idle.
then adjust your high speed as needed.

if it is stalling out after 10 to 20 seconds while idling, sounds like a bad check valve. these may or may not be replaceable, do not know for sure."

I am guessing this check valve is somewhere in the fuel supply circuit.  Just adding this in case anyone has some additional insight.  Thanks again, Dave

[Iwawoodwork]

Did the mechanic try the carb exchange with a known working carb?  That would show if the issue is directly related to the carb and reduce the chance that you would be spending a $100 for nothing.

[Dave41A]

Did the mechanic try the carb exchange with a known working carb?  That would show if the issue is directly related to the carb and reduce the chance that you would be spending a $100 for nothing.

I had that thought.  Apparently the decision "it needs a new carb" came from the ECHO tech, over the phone.  I will ask your question the next time I speak to the mechanic.  This seems a little like a $100 gamble to me.  Dave

[kenskip1]

Well dave,it has been almost another month.Has Echo been in contact with you?Honestly if this was me I would have another saw buy now.It should not take this long. Even for a carburetor. I really believe that the folks at Echo are hoping that you will loose interest and forget about the whole thing.I hope that I am wrong but I doubt it, Ken