Chainsaw wont start

metalman1 · March 17, 2019, 02:03:29 PM

People,

Have a 20 yr old Poulan 2150. Ran well until now - will not start. So I did the usual remove gas, remove carb, clean carb out, inspect diaphram, verified spark plug sparks (in a dark room), and to eliminate any potential problems that would be caused by the carb/carb tubing I sprayed some starter fluid directly into the carb. Pulled and pulled, with no luck. I understand a piston needs to generate at least 100psi to get any fire. Is that true? Could this be my problem? I dont have a compression tester.

Thanks.

Greenerpastures · March 17, 2019, 05:52:51 PM

Hi metalman1
I know nothing of that model saw, but you say it ran fine until now,
might help the others who know these saws if you could explain a bit more
regarding when the saw was running last, has it been sitting up for long,
is there a spark screen in the saw, a real dirty one can make starting real hard.
Is there a decompression valve, is it closed or stuck open, will the saw drop to the ground
if you hold it up by the pull cord, if so compression may be low.
Can you change out that spark plug for a known good one, or put it in a different
saw that it fits and see if it runs, spark plugs can play tricks, can fail under compression,
can loose connectivity if they are damaged where we can not see it, way up the electrode.
Was your carb diaphragm stiff, that wont help either, it may have no leaks but stiff is no good either.
I would take a chance and tip a good amount of fuel into the plug hole and see what happens, never know, if she kicks well and good.
If your saw sat up the rings could be seized, they could be seized because the last time it ran so well it was because the saw was hot and tightening up, may be take off the muffler and look in to see what the story is, hopefully it will be good and no scores or stuck rings.

Hope you get sorted

metalman1 · March 17, 2019, 07:03:13 PM

Wow, greener, so much good info. I will explain further- Saw ran last on last Hurricane, 8/2017. How can I tell if there is a spark screen? Maybe I can google it.

Decomp valve? Beats me, I dont know what one looks like. I can google that one too for a picture.

Maybe I should buy new plug, as it has been 20+ years. It is original. regarding carb diaphram, if I use starter fluid directly into the carb shouldnt that bypass the diaphram?

Here is my saw, with diagrams, I could not find any such decomp valve. I believe it is only on higher quality saws:

Poulan Gas Chain Saw | 2150 | eReplacementParts.com

Just tried your trick of holding the cord, and letting the saw hand and geez- it drops by itself kind of slowly, like a heart beat- lub dub (pause)lub dub (pause) lub dub, and repeats, eventually falling to the ground!! Bad comp?

Good idea about putting some fuel into plug hole. I will try that tomorrow and let you know!

Thanks, Greener.

Gary Davis · March 17, 2019, 07:08:34 PM

If it has compression check the spark plug first

lxskllr · March 17, 2019, 07:12:11 PM

The spark arrestor is inside the muffler. Usually the last thing before the exhaust hits open air. There'll typically be an easy way to remove it for cleaning(a couple screws or something).

I don't believe that saw will have a decomp. If it does, it's just a button you push when pulling the saw over. It reduces the compression, making it easier to pull. They can fail, and drop parts in the motor, or leak causing the saw to run poorly, but as I said, I don't think yours has one.

dougand3 · March 17, 2019, 07:38:55 PM

This is a simple muffler - not even a screen. 2 8mm head bolts and muffler comes off. You can inspect piston and ring.
Avoid ether starting fluid - you wash lube away. Use fuel mix.
Dribble a tsp into plug hole, re-insert plug and pull rope 10+ times. You want a 1-2 sec fast run. If so, you have a fuel delivery problem-carb, fuel lines.
If no joy, put a tsp of 90wt gear oil on top of piston, work oil around to sides of piston. Add a tsp of fuel mix. Re-insert plug. Pull again 10-20x. If you get a 1-2 sec run, you have low compression.

metalman1 · March 17, 2019, 07:57:15 PM

Great Tips, people! Cant wait to try these ideas! Will do this tomorrow and let yous alll know what happens.

Greenerpastures · March 18, 2019, 01:32:19 PM

Quote from: metalman1 on March 17, 2019, 07:03:13 PM
Wow, greener, so much good info. I will explain further- Saw ran last on last Hurricane, 8/2017. How can I tell if there is a spark screen? Maybe I can google it.

Decomp valve? Beats me, I dont know what one looks like. I can google that one too for a picture.

Maybe I should buy new plug, as it has been 20+ years. It is original. regarding carb diaphram, if I use starter fluid directly into the carb shouldnt that bypass the diaphram?

Here is my saw, with diagrams, I could not find any such decomp valve. I believe it is only on higher quality saws:

Poulan Gas Chain Saw | 2150 | eReplacementParts.com

Just tried your trick of holding the cord, and letting the saw hand and geez- it drops by itself kind of slowly, like a heart beat- lub dub (pause)lub dub (pause) lub dub, and repeats, eventually falling to the ground!! Bad comp?

Good idea about putting some fuel into plug hole. I will try that tomorrow and let you know!

Thanks, Greener.

Sounds like you have some compression, hopefully enough, bad bearings can also bind enough to give similar result, but there would be a different and not good noise to indicate this, bad bearing trail around instead of roiling and make a noise, but hopefully it is compression that is holding your saw up and lowering it in stages towards the ground.
Like others said, try some fuel poured in the plug hole, if it kicks off for a second or two and then dies, its like fuel not getting to the engine, there is a filter in the tank, take off the tank cap, put a wire with a hook on the end into the tank and get the filter out of the hole, check its not blocked.
If no go after pouring in the fuel, dry plug, and as mentioned put a tea spoon of oil. engine oil or gear oil, in the plug hole, try to ensure the piston is near the top so the oil does not run out the exhaust, move the saw around so the oil runs around the piston top, the idea is to seal the rings if they are worn, then put some mixed fuel in the plug hole, put plug back in and try to start, if it fires up for a second or two and dies, its fuel for sure, and a little low on compression.
Let us know what you try and what the result is, but given your saw lay up, the rings could even be seized, or the carb clogged or the diaphragm is hard instead of soft and pliable.
Don't be put off by what could be wrong, any one simple thing can cause it not to start and these suggestions are only to cover those possibilities.

metalman1 · March 19, 2019, 04:48:17 PM

Well, I tried both ways, and still no start. Sheesh. I will try one last thing- have a local shop test for compression (for free), and buy a new plug. I will advise asap, people.

Greenerpastures · March 19, 2019, 05:03:05 PM

If you put oil in the plug hole, and put some fuel in there too, you would nearly pull you fingers off trying to pull the cord, did this happen, or was it as if nothing changed.

Did you take off the spark screen, was it clean or blocked, did you remove the exhaust to check if there was signs of scoring on the piston, or rings, you would also see if the rings were stuck, all this can be seen through the hole when you take the exhaust off, if scoring is found, then you would have to assess whether or not to try and fix the saw, a saw shop would need paid, and whether that is worth it to you or not is a matter to think about.

Regardless, the compression test will tell its own story, hopefully a good one.

metalman1 · March 23, 2019, 11:53:26 AM

Quote from: Greenerpastures on March 19, 2019, 05:03:05 PM
If you put oil in the plug hole, and put some fuel in there too, you would nearly pull you fingers off trying to pull the cord, did this happen, or was it as if nothing changed.

Did you take off the spark screen, was it clean or blocked, did you remove the exhaust to check if there was signs of scoring on the piston, or rings, you would also see if the rings were stuck, all this can be seen through the hole when you take the exhaust off, if scoring is found, then you would have to assess whether or not to try and fix the saw, a saw shop would need paid, and whether that is worth it to you or not is a matter to think about.

Regardless, the compression test will tell its own story, hopefully a good one.

Thanks, Greener. Sorry for delay, been busy, but it finally started!! I didnt even go to a shop for a comp test! Yipeeee! So, I just crossed my fingers, saw sat for days, and pushed primer bulb, held down throttle, and pulled, and it started. I even revved it up to high rpm's, and it ran well. It ran for only about 5-6 seconds though and quit. So, Im assuming comp is good, spark is good, fuel has to be good (right??). Carb has to be getting fuel because I removed the tiny tubing and pressed the primer button and it spurted fuel. So, now, not sure why it is quitting after 5 seconds. Anyway, getting close, right?? Tips appreciated.

sawguy21 · March 23, 2019, 12:04:49 PM

Fuel is getting TO the carburetor but not through it. You say the diaphragms are original, they will be hardened with age. Has the saw been sitting unused for a long period of time? I suggest replacing the carb, they are so cheap they are not worth rebuilding

dougand3 · March 23, 2019, 12:11:24 PM

1. Carb diaphragms stiff.
2. Carb screen dirty/varnished.
3. Fuel lines hard/cracked or too soft.

Online, a new carb is $9 or $12 for a whole fuel delivery kit. Search "Poulan 2150 carburetor"
These carbs aren't worth cleaning and a RB kit when the new carb is so cheap.
If your lines are brownish and hard or too soft/gooey, worth the whole kit.

metalman1 · March 23, 2019, 12:57:00 PM

Quote from: sawguy21 on March 23, 2019, 12:04:49 PM
Fuel is getting TO the carburetor but not through it. You say the diaphragms are original, they will be hardened with age. Has the saw been sitting unused for a long period of time? I suggest replacing the carb, they are so cheap they are not worth rebuilding

Right, sawguy. diaphram IS original, from 1998. Got to be a big suspect. So, the saw is starting but , I guess, one way to describe it is the saw is "starving" for continued fuel supply? Youve convinced me to buy a new carb, maybe not even trying to rebuild......

metalman1 · March 23, 2019, 01:00:41 PM

Quote from: dougand3 on March 23, 2019, 12:11:24 PM
1. Carb diaphragms stiff.
2. Carb screen dirty/varnished.
3. Fuel lines hard/cracked or too soft.

Online, a new carb is $9 or $12 for a whole fuel delivery kit. Search "Poulan 2150 carburetor"
These carbs aren't worth cleaning and a RB kit when the new carb is so cheap.
If your lines are brownish and hard or too soft/gooey, worth the whole kit.

Thanks, Doug. Yes, all tubing IS brown! Youd you know??

! Yours is another post recommending a new carb AND tubing. Good deaL. iM GONNA SEARCH AND BUY ASAP.

Found this link:

Amazon.com: poulan 2150 carburetor kit

My carb says WT-324 Walbro. Which one would you buy if you were me?

tHANKS, PEOPLE!

dougand3 · March 23, 2019, 04:42:51 PM

You need the top one listed- $12.98. NOT the 2 butterfly carb - that's strato - 2005 and newer.

metalman1 · March 23, 2019, 07:17:18 PM

Quote from: dougand3 on March 23, 2019, 04:42:51 PM
You need the top one listed- $12.98. NOT the 2 butterfly carb - that's strato - 2005 and newer.

Geez, Doug, I must be missing something as I cant see any item for the $12.98 amount. Top one is not $12.98. Idea- maybe you can click the item and post the link? Would be huge help........
Thanks!!

dougand3 · March 23, 2019, 07:22:46 PM

The top one changed price to $14.99 - odd.
This one is fine.
Amazon.com: Carburetor Air Filter Carb Fuel Line Spark Plug Carb For Poulan Chainsaw 1950 2050 2150 2375 Wild Thing 2375LE Walbro WT 89 891 WT-324 Zama C1U-W8 C1U-W14 Replace# 545081885: Garden & Outdoor

metalman1 · March 23, 2019, 07:31:31 PM

Quote from: dougand3 on March 23, 2019, 07:22:46 PM
The top one changed price to $14.99 - odd.
This one is fine.
Amazon.com: Carburetor Air Filter Carb Fuel Line Spark Plug Carb For Poulan Chainsaw 1950 2050 2150 2375 Wild Thing 2375LE Walbro WT 89 891 WT-324 Zama C1U-W8 C1U-W14 Replace# 545081885: Garden & Outdoor

! So goofy of Amazon to do that, Doug! Anyway, I got it now! Gonna order it asap! Thanks for the super fast reply. You guys are sooo helpful!

metalman1 · March 27, 2019, 09:04:06 AM

Got the new carb, and it looks nothing like my original one. Please not the original (Left, with blue choke lever still attached) shows both brass gas lines on one side, unlike new one on right (showing one on each opposing side). Also, there is an additional "lever" on the new one next to the choke lever. Anyone know why? Can I still use this new carb? Do I have to return it, people?

Thanks!!

dougand3 · March 27, 2019, 09:49:11 AM

That's the correct carb. New ones have the extra choke bracket, which is the high idle setting. It works better than the handle button you have on the saw. Only possible problem is it may hit the air filter housing - some have a cut out for the extra part, some don't. I either cut/grind off any metal hitting black plastic or add a thick plastic gasket between carb and air filter housing.

The 90* nipple is the line to the short purge tube. The straight nipple line goes to the fuel tank hole.

metalman1 · March 27, 2019, 10:12:30 AM

Quote from: dougand3 on March 27, 2019, 09:49:11 AM
That's the correct carb. New ones have the extra choke bracket, which is the high idle setting. It works better than the handle button you have on the saw. Only possible problem is it may hit the air filter housing - some have a cut out for the extra part, some don't. I either cut/grind off any metal hitting black plastic or add a thick plastic gasket between carb and air filter housing.

The 90* nipple is the line to the short purge tube. The straight nipple line goes to the fuel tank hole.

Whew, (wiping sweat from forehead with left hand), glad to hear that, Doug! I will proceed!!

metalman1 · March 27, 2019, 06:28:10 PM

Quote from: dougand3 on March 27, 2019, 09:49:11 AM
That's the correct carb. New ones have the extra choke bracket, which is the high idle setting. It works better than the handle button you have on the saw. Only possible problem is it may hit the air filter housing - some have a cut out for the extra part, some don't. I either cut/grind off any metal hitting black plastic or add a thick plastic gasket between carb and air filter housing.

The 90* nipple is the line to the short purge tube. The straight nipple line goes to the fuel tank hole.

Doug, thanks in advance for your patience. I just dont understand this "extra choke bracket" gismo. It seems to hook onto the other lever, y a spring,. not allowing me to use the original design. Should I worry to much about this "new function"? Would you remove the original blue plastic choke handle button and pop into the hole in the new carb? If not, how does one choke? Maybe dumb questions, from a greenhorn........
Heck- worst case- I install the new carb and try it out. Can always remove........

dougand3 · March 27, 2019, 07:15:07 PM

The extra brackets are High Idle Setting. Play with it - engage choke and watch throttle plate - see that it rotates off the tapered idle screw. Rotate throttle plate and see that HIS pops off and throttle plate returns to touch idle screw. That's what High Idle is - lotsa fuel to get an easier cold start.
Stick the choke rod in hole like normal and put carb on. The only problem is if HIS metal hits back of air filter housing and choke won't pull. You have to cut/grind extraneous metal off or put a thick gasket between carb and AF housing.
I've cut part of the AF housing plastic away to make room for choke/HIS metal. I just covered hole inside with loose duct tape and shaved off some of the sponge filter, so it wouldn't be too thick there.

Play with it and think about what functions are.

metalman1 · March 29, 2019, 05:29:04 PM

Quote from: dougand3 on March 27, 2019, 07:15:07 PM
The extra brackets are High Idle Setting. Play with it - engage choke and watch throttle plate - see that it rotates off the tapered idle screw. Rotate throttle plate and see that HIS pops off and throttle plate returns to touch idle screw. That's what High Idle is - lotsa fuel to get an easier cold start.
Stick the choke rod in hole like normal and put carb on. The only problem is if HIS metal hits back of air filter housing and choke won't pull. You have to cut/grind extraneous metal off or put a thick gasket between carb and AF housing.
I've cut part of the AF housing plastic away to make room for choke/HIS metal. I just covered hole inside with loose duct tape and shaved off some of the sponge filter, so it wouldn't be too thick there.

Play with it and think about what functions are.

Almost there, Doug. Only snag now is when I set in the carb, and test try the linkage where the throttle plate returns/snaps back to rest on the idle screw- right there, the factory shaped link kinks and binds against the bent 90 degree brass fuel nipple such as when I press the release (at the handle) it doesnt snap back cleanly cuz it rubs against that L shapes fuel inlet. The linkage is BELOW the fuel inlet. Should I try to bend it? Bend the L shaped (90 deg) fuel inlet instead? I dont think forcing it to run on TOP of the 90 deg fuel inlet would work(?). This may be my last challenge with this, Doug.