Stihl 462CM Hard Cold Start

[axeman2021]

Sometimes I use the compression release. sometimes not.

I called Stihl USA, the mothership, and had a good conversation with the tech rep.  Basically, he thinks I've got a fuel starvation issue, and am losing prime.  I didn't disagree. Also, since I've had my saw more than 3 months, and I'm a business, its out of warranty, which was a surprise to me.  I thought it had a two year warranty, but I was mistaken.  So I'm on my own, so to speak. Even a dealer diagnostics test costs money out of my pocket at this point, so now I'm looking at this in a new light.  

He suggested I could shotgun the problem, and I should sequentially replace the fuel filter, air filter, spark plug, carburetor, fuel line and finally the solenoid.  Yeah, right.  I told him I may as well replace the entire saw.  He also suggested I take it to my nearby John Deere dealership, apparently they are authorized dealers and repair facilities and have the proper training and computers, whereas other dealers, like mine where I bought the saw, don't or may not have the depth of knowledge or the equipment.  We discussed this option, which I wasn't really aware of, and I agree that it's probably best to take it to a service facility where they have professional mechanics working on tractor engines, vs at a hardware store where the mechanic may not be as experienced.  This opens up repair options for me, as I have a Deere dealer not to far away.  I called them and they do have repair equipment but couldn't give me an estimated turn around time for the repairs.

So after that conversation, I decided it was up to me to try the simple stuff, and just go through the saw as any other unwarranted piece of equipment I own, and try to diagnose and fix the problems myself.  I uploaded a useful semi diagnostic document on the internet from Stihl that helped me understand the Mtronic system a little better, and I went through the saw from stem to stern and found a wire that was loose and a few other things.  I disconnected and reconnected electrical connections, any fuel lines I could reach, tightened every nut and bolt I could find, and fiddled with anything else I could play with, because at this point, I sure don't need to worry about voiding the warranty.  My air filter was clean, but had a little oil in it, from the inside.  I'm not sure what that means, if anything.  

After playing with it for awhile, and buttoning everything back up, it cranked on the third pull, cold, which was surprising to me.  It's never done that before.  I'll check tomorrow and see if it's fixed, or was just teasing me.

I have called around and found a shop that's about 2 hours away that has 500i chainsaws and doesn't take trades, which wasn't a good option, and another shop about the same distance in the other direction that has several 500i's in stock that does take trades, but, (nothing is easy) their saws were shipped without mufflers, for emissions reasons the guy said, and they have been waiting about 2 months for the mufflers to arrive.  So that's a better scenario, and I need to get this saw either running smoothly until they come in and trade it off, or put it on the shelf and pick up another saw, until someone has a 500i and takes trades.  I don't want to Craigslist it off, because I don't want to do that to an unwary buyer, and sell my problem to them.  

This is a really nice saw to use, I like it, or I wouldn't still be putting effort into it, but I just have to work through the cold start issue.    

Anyways, I learned a few things, so the process continues.    

Would you give use the link to the stihl Mtronic diagnostic document?

[doc henderson]

one of our eagle scouts works at a dealer in "the south"  and has done me many favors.  I am checking to see where.  I have done he and his family a few as well.  My dealer went through a regional rep with my 660 I returned.  the dealer did it on his own on my 261 as I am a good customer.  

[doc henderson]

My buddy lives about 7 hours drive from you.  so too far, but i am asking for advice, and or contacts closer to you.

[nativewolf]

@YellowHammer Sorry to hear of your woes.  We had a boatload of issues that were fuel related.  

We bought ours through our very local dealer and thank goodness, had 4 of them.  1 we crushed underneath a forwarder (opps), one blew up, one is junked.  If I had to do it again we'd use premixed fuel only.  I think something is wrong with the fuel solenoids, solenoids are not expensive; on one saw it and the top end were replaced under warranty as the solenoid had failed (this was the first 462 repair under warranty in the USA- not the claim to fame you want).  Stihl's regional rep was great to work with, he supported our local dealer all the way.  

Recently we've had a 500i just stop working...nothing.  Complete diagnostic says everything is ok- like new, but it won't run.  Just cut off.  My son did not even try to restart just took to our dealer.  2 weeks old.  That was a great saw too, really nice power/weight/balance.  I'd buy that before buying another 462cm.  I much preferred the 500i and I think they've got a real keeper.  

So I think that the Stihl solenoids have some issues with certain pump gas mix- our fuel never sat more than a couple of days, we kept out of the rain and only used synthetic oil, et.  Others like @ehp  are very pleased, he has a steady source of high quality fuel and uses a high quality mix.  Our stihl dealer is great, his dad sharpens our chains (we're only hand sharpening once, must have 100 chains in rotation), his mom grew up next door to our farm, etc.  Good relationship.  Our solution has been to buy a pallet of premixed 94 octane ethanol free moto fuel.  We'll get the 500i back soon.  Our 362 never had the same issues as the 462/661 or 500i so I suspect a change in solenoid manufacturers sometime, the 362 is the oldest of them all and is my favorite, favorite topping saw.  Use it all day and not fell tired (I'm 53 and this means maybe 10 tanks of fuel- for me that's a good days work).  It never complains about fuel, everything is just great.  

I believe the 500i is going to be a real winner but our local fuel issues have forced me into the pre mixed fuel route.  

[ehp]

ya  you guys got bad fuel, I have not had a fuel problem in alot of years like I'm guessing 15 years . One thing I'm not sure many know but saws like the 500i has its own fuel filter and you have to use that fuel filter , it has a magnet inside it to pick up the very fine metal that is in today fuel, that is why alot of the fuel solenoids fail 

[YellowHammer]

I'll try the pre mix route, I've never done that, and never had to.  $20 bucks a gallon?  ouch.  I'm using unleaded non ethanol premium.  If the saw won't run on that, jeez. 

I really like my dealer, but he is out of his league with the newer says, and he admits it, and doesn't even have the diagnostics equipment.  So I need to find a new dealer I can trust. Or just go back to a carburetor saw.

I'd buy a 500i for the heck of it, but I can't even get close to finding one around here.  The nearest is several hours drive away, and they won't take a trade in.  

I was looking at the diagnostic link on the web, and it had Stihl confidential so I shouldn't post it. 

[Skeans1]

Just kind of curious how much fuel are you guys running through and how are you storing your fuel?

[barbender]

I'm very thankful for the quality non-ethanol fuel we have available. I've never had a fuel quality issue.

[YellowHammer]

I go through a 5 gallon jug every few weeks.  

[Skeans1]

@YellowHammer 
So not a ton, is the can stored inside a warm area?

[donbj]

Something is going on with this whole fuel thing. A guy should not have to buy premix so his saws will run! Something f'd up with that. Some fuel lasts a month, some 6. Put ethanol in, better stay on it.

I have literally have saws that have sat for 30 years with a tank of fuel. When opened it was literally oil in the tank. Inside the carbs was just oily residue, no corrosion or such. A quick clean and many ran fine aside from maybe stiff diaphram or something. Certainly nothing like the risk of leaving fuel in a saw for more than a couple months these days. What gives with this?

[barbender]

I agree and I'm glad that our local fuel hasn't had these issues. If you get the non-ethanol premium and don't get water in it, it seems to stay pretty stable. I have saws that often go 3 months without being started, and I haven't had fuel problems with them.

[nativewolf]

Clearly we do have some fuel issues, we went 6 months offsite without issues but locally...we have issues.   That said the dealers advice running high octane fuel in these saws.  High octane ethanol free is not available to us.  So, we are just going for the pre mixed.  I actually don't live that close to a gas station (20 mins) and not having to make trips, mix, bring home etc will help offset the high cost of the mix fuel.  We'll buy a pallet a couple of times a year.

@skeans1 has suggested to us that it is critical to keep the fuel out of weather and warm. We don't have a heated garage so in the winter it got cold.  

@ehp- yes we only use the stihl filters.  I change them once in a while. 

Our dealer was sent diagnostic software to analyze the saws, it is pretty neat actually.  I'm sure that Stihl is going to figure all of this out.  Many people are very happy with them but others have issues, I can only surmise that they have some supplier solenoid issues, maybe 2 providers? or QA issues.  I do know that on the 1 462 it was a solenoid that had failed and that Stihl changed solenoid parts and fuel filters in all 462s about one year into sales here in the USA.  I have now found that they have done parts changes on the 661.  We have two 661s and they have different parts on the top end.

[YellowHammer]

I agree on the fuels thing, I have quite a few 2 stroke engines and very demanding 4 stroke small engines, and never had a fuel issue with them.  The fuel is stored inside my shop, it 70F, mixed with Stihl oil, and I have been running it for years and years, and this is the first time I've had a problem with it.  My 661 loves it, as does my 372, my pole saw, backpack blowers, and other stuff. As I can tell this saw does as well, because when it starts, it runs like a scalded dog, no smoke, nothing.  However, I might get some and try it. 

I still think this is some sort of prime issue, yesterday, it burped then died on the third pull, but when it died, now that I'm getting to understand it, it sounded fuel starved.  I got it cranked 6 pulls later, and as soon is it hit, I immediately killed it, maybe one heartbeat at most.  So I knew I had fuel to the carb and as far as I was concerned, it was now fully primed.  I gave it one short tug, and it roared to life.  It wanted to run.

I'm going to try the slow pull throughs today, until I can smell fuel, maybe a half dozen or so.  I also need to do some more reading on some of the diagnostic tests, are there are vacuum tests, fuel line bleed down tests, etc, and it's not like this is an emergency, it's just an annoyance.

  

[weimedog]

ya  you guys got bad fuel, I have not had a fuel problem in alot of years like I'm guessing 15 years . One thing I'm not sure many know but saws like the 500i has its own fuel filter and you have to use that fuel filter , it has a magnet inside it to pick up the very fine metal that is in today fuel, that is why alot of the fuel solenoids fail

This a Stihl issue? Or Husqvarna as well? I haven't seen any of the Autotunes have issues in this way but have seen some M-tronic solenoid issues locally here, but not so many that it's raised a flag. Figured they should be similar so should I be expecting something similar to show up?? I've been running ( my customers as well ) just the non ethanol 89 octane from the pump at 32:1 or 40:1 with Husqvarna oil...no issues any where in the community of saws I support. All Husky.  

[Skeans1]

@nativewolf 
@YellowHammer 
I've ran autotune saws since 2011 both of which have had nothing but a straight diet of ethonal fuel put through them with a lot of gallons of fuel burnt through both. When I think of going through fuel I think of 4 gallons a week any longer and it's probably time to toss it out. 

Native-
What octane is this can fuel you're running? Running a higher octane can cause just as many problems as running to low of an octane.

Yellow-
I wonder if the diaphragm in the carb has a tear or isn't placed correctly.

[doc henderson]

lots of M-tronic problems, and not many dealers will admit it.  I am fortunate to have a straight shootin dealer, and a friend who works at an outdoor equipment dealer that carries Stihl.  they have told me there are issues.  these are issues that happen when you engineer something way beyond the pale trying to save 2 drops of fuel (or comply with all the sudden regulation by the government) per day.  I will prob. never buy another 3 position start saw.  the dealer thinks they have improved the m-tronic solenoid, but does that mean they are perfected?  the dealers techs do not all know how to test them.  and often they will say they tested normal.  My dealer finally just put a new one on my 261cm, and no troubles since.  it is a problem if you run them out of fuel.  overengineered finicky.  He know they have a problem with the metering solenoid.  they should not loose prime, unless you run it out of fuel.  If I had to pay for it, I would tell to skip the diagnostics and just replace the solenoid with the new and improved one.  then when it fixes (hopefully) the problem, go back and tell them it must have been that way from the factory.  If you your dealer still denies a problem, I would find a new dealer.

[mike_belben]

High octane has a higher autoignition temp and flash point.  Its benefit is that it takes more temp to detonate which is when the entire charge goes off simultaneously.  This is the rattley marbles in a coffee can sound grandads old ford marquis had lugging up a hill.  It is uncontrolled combustion. Like a grenade.  Very hard on top rod bearings, rings and wrist pins.


Controlled combustion is like a rock in the center of a pond making ripples (of temp rise, flame wave and expansion that then compress the next layer of fuel/air mix which repeats the sequence) all the way to the shores .. In this case the cylinder wall.


High octane is for severe application.. Either a bandaid fix for a terrible knock prone cylinder design like say old open chamber V8s with no squish pad, or the worst, original hemi or toyota 22r.. That half an orange shape with a huge pop up piston.  

Or high octane is for performance components..  I dont mean oem parts and performance use or abuse.. Properly designed oem parts will take all the throttle you can offer on 87 without fail.  I mean 10:1+ pistons then a turbo with 10psi or more ontop of that.  Or 11.5+ compression NA and sahara roadracing.  Thats gonna require an octane repair.  Dyno queens... They can pour on ignition timing and boost boost boost to hit the number if they have enough octane to keep detonation off. 



All this stock stuff will run and will run well on 87 octane because it burns faster (which prevents knock) and chamber designs and knock sensors today are such that we do not need octane or lead to bandaid fix bad combustion shapes or ignition timing or injection quantities of 1988.

  Besides all that, 2 strokes spin so fast that detonation has really never ever been an issue.  You dont touch wood at idle like a pickup truck with a trailer leaving a stop light and going easy on the clutch.  Low RPM makes slow cycles and slow cycles take long time. Long time lets hot bores raise fuel/air temps hotter and low octanes go bang when autoignition temp is achieved.  High octane is unnecessary in a saw.  Its for a 4 stroke problem.  


As for ethanol, i have had it turn to jelly in vented float bowls that have sat parked for 3+ months.  Ive had it jellify very old fuel lines on stuff that was manufactured before ethanol. Ive never had it fail to run in a saw within 2 months of purchase.. A clearish color is what i go by.  When it starts to look like a coors light it becomes partswasher solvent.   i have both vented and unvented cans in a very humid climate with major temp swing condensate.


Purely a guess here.. I suspect in the majority of cases, the saws are the issue and the fuel a convenient and unpopular scapegoat to cover some incredibly expensive recalls.  I have been on the interior of a corporate manufacturers policies of blame the customer at all costs before and this smells similar.

[ehp]

Yes you changed the fuel filters but were they the correct filter for that saw not the brand   . Like I said lots of dealers donot even know that you have to use a certain filter for that certain saw.  

No its a fuel problem . Lots of weed wackers have the same problem with the screen in the carb getting plugged solid of a very fine red dust . One fuel brand is by far the worst and lawn guys that do it for a living pretty much every 2 weeks get that screen cleaned as they run them 50 plus hours a week .

No husky has problems to cause its the fuel not the saw  fault .

I burn 2 to 3 gallons a day unless it's big timber then I burn more .  

I got saws here that are 6 or more years old that are auto autotune and zero problems as far as fuel .  I donot even change fuel filters hardly ever. If I got to put a fuel line in yes I change the filter .  

In my small group of guys I'm sure we got to own close to 30 mtronic or autotune saws and run saws everyday and no problems so it's the fuel I would have to guess . The last saw that had a problem was a 441 stihl that Pete bought and after 2 rounds of it screwing up it got sent down the road back to the dealer and he came back with a 461.   Like I said I buy my fuel from one place and it's a crazy price but zero problems.  Fuel right now is $1.60 a litre so pretty close to your quart.   It's 94 octane and I run klotz oil at 40 to 1 

[barbender]

Ed, which Klotz do you run? 

[nativewolf]

For the next 6 months we're just using the premix ethanol free 94 octane moto fuel.  To heck with it.  More expensive but if it saves 1 trip to the dealer it is worth it.  If it saves a trip a week to buy 7.5 gallons of fuel it is probably worth it, get another tree down in that time.  Heck I can plant 30-40 trees in the same time.  

What I've learned on here is that we've got an abnormal situation and it exist across a variety of higher end Stihl products.  Not the 362cm which is also autotune.  Never had issues with them, always just get up and go.  So something...something is going on.

On the other hand...great dealer, he even sent us a client or two.  So it all goes under giant PITA rather than critical business failure.

[mike_belben]

Just remember, If your next saw burns up on the VP its time to throw the fuel theory out.  


My money is still on 50:1 being too lean, and saw fans not working when the bar is buried in the dirt and muffler blowing at the bark for a lengthy veneer borecut.  The heat gets trapped around the saw and the fans CFM plummets due to the grounds priximity restricting airflow.  The air temp between the saw and the dirt doubles, thus the delta T halves, more or less. 

 reduced exterior cooling efficiency.  air filter plugging up from the fine dust reduces the interior cooling efficiency from lower CFM passing through the machine.  
 

All additive.  Result is aluminum melting threshold is achieved on the exhaust side right at the ring land and spreading from there.  Not enough lube to prevent transfer. 



A temp gun.. Or even better a thermocouple datalogger clipped to the fins would make it quit obvious for charty folks.


Id fatten the fuel oil up, muffler mod if possible and give it idle breaks, especially after a bore cut.

[doc henderson]

I stick with Stihl cause I have a great dealer.  I think if the fuel was the only or major problem, the saw would not run so good after it starts.  I have been told by several in the Stihl world that it is known that the meters are finicky, and you might get a good one and you might not. My fuel is mixed with the stihl silver oil and can take me 6 months to use 2.5 gallons.  when running right, the fuel had never been an issue to my knowledge.   they have continued to improve them and after taking it in 3 times to find them saying the solenoid tests normal, the dealer replaced it with the latest gen new version and no problems since.  all using the same fuel.  

[barbender]

Mike, Mike! Whoa! Delta T halving? I'm simple, I was flying in my little bi-plane, we were cruising together until you just put the hammer down and I realized you were in a fighter jet!😂

[mike_belben]

Pew pew!

air_plane

When the saw is plunged into the tree with the powerhead blowing down into the weeds its like going from canada to africa in terms of ambient temp that the saw is feeling.