Stihl MS362 problems

[callan]

Hey Everybody,

I'm having some issues with my 362, and quite honestly, have had them since it was new. I kept hoping they would resolve themselves after a good break-in period, but I'm way past that now. Sorry in advance for the long post, but I figure the more information the better.

Problems with the saw
-The saw starts just fine when it is cold, but after running a while, especially in 90+ degree weather it is really hard to get started. I have to put it in the shade for a good 15-20 minutes to let it cool down sometimes.
-If you hop on the throttle, without easing into it, it will blubber out and die. You have to put extremely light pressure on the throttle, and slowly rev it up. This happens even after the saw is fully warmed up.
-It sometimes seems as though the chain or sprocket is stuck. One guy told me I had a bent bar, because just after starting it, the chain does not always move freely. I have tried new bars and chains with the same result.
-The saw bogs down very easily in all types of wood. Sometimes it will bog down, and then die. If this happens on a hot summer day, I have to let the saw rest in the shade before I can restart it and continue working (a real pita).

About the saw
It is a Stihl MS 362, bought brand new in April of 2012. I run a 20" Stihl bar with a Stihl Rapid Super chain. I use Premium unleaded with up to 10% ethanol added (can't find anything else around here). I am at high altitude (6,000 feet), but the carb is supposedly adjusted accordingly. I can get it running pretty good if I fiddle with the carb a little bit, but it seems to only last about 15 minutes, and kind of reverts to how it was running before. BTW, it has nothing to do with how sharp the chain is, or if the rakers have been properly filed. That has been accounted for.

I took it back to the dealer a couple times, and they adjusted the carb, told me it might be the ethanol content in the fuel that I was using, and basically said nothing was wrong. Although I have run other 362's with none of these issues, I took them at their word, because I'm not really a mechanic. After no improvement, and over a year of use, I called Stihl, they gave me a different dealer to take it to. They ran a "Stihl Engine Check", cleaned everything, replaced the spark plug, re-adjusted the carburetor, and sent me on my way. Of course, they had me test it out at the shop, and it seemed fine, but after I got it on the job site, it was quickly back to it's old ways.

Is there a chance that I just got a "lemon" from the factory? If I can't find any answers, I guess I'll sell it and try to get another one. I'm at my wit's end. Any help or advice is GREATLY appreciated. Thanks!

 

[7sleeper]

Retune the carb at your worksite.

7

 

[AKDoug]

Here is the deal, and if you don't have much experience be careful. Your saw is most likely running too rich. The heat and altitude results in air that has less oxygen available than air at cooler temps and lower altitude. When running at high altitude and high temperature, you will need to lean your saw's mixture to get it to run correctly. It might only take as little as 1/8 turn clockwise on the H and L screws to get things corrected. It is lined out in your owner's manual and there are numerous threads on tuning here and elsewhere on the net. There are times that a dealer may be operating at a lower altitude, or different temp, and that makes it hard for them to tune a saw for you. There is also the chance your dealer has no clue too I believe your chain and power issues are directly related to your tuning issues.

Oh, and one last thing. Pull the screen out of your muffler and see how clean it is. It's the single screw on the muffler, then it slides out.

 

[z71mike]

Sounds lean to me. Overheating then cooling down in the shade to run normal again.

I agree with tuning at the job site.

 

[XSKIER]

Is the dealer at a different altitude than you? Over 90° at 6K feet, I'll bet your fuel is boiling. Try trufuel, after looking for cylinder scoring.

 

[VASAW]

TOO HOT!!!!!!!

 

[Andyshine77]

Sounds like the saw may be down on compression. Pop the muffler off and have a look at the cylinder.

 

[callan]

Lol Doug, most of the time I feel like the dealer has no clue what they're doing When I took it in, they said it was probably the fact that my chain was dull. Yeah, thanks for the observation, I just got finished cutting into a tree with a damn brick in the middle...not the problem.

Thanks for the replies, and here are a few more clues. Most of my frustration lies in the fact that the saw bogs down and dies when I am cutting, and the fact that I have terrible throttle response. I do retune at the job site, but it seems to come out of tune very quickly. I have cleaned the spark arrester, should I totally remove it? The dealer is at the same altitude as me, and supposedly a gold certified stihl repair shop which just completed a stihl engine check. I'm assuming that the cylinder was checked, but if I wanted to do that myself, Andy, what exactly would I be looking for?

Is there something that would cause the saw to come out of tune after 10-15 minutes of cutting? My 044 runs like a champ, in the same conditions, and never comes out of tune.

 

[z71mike]

If it won't hold a tune, you may have an air leak somewhere. Start with a pressure/vac test.

 

[AKDoug]

I would have bet it was a lean problem if it wasn't for the temp and altitude. It still could be a lean problem like an air leak, but that shouldn't happen after 15 minutes of run time. Any leaks should have been found if the tech did the engine check correctly.

To check the front of the piston/cylinder for scoring you simply have to remove the muffler and look.


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[AKDoug]

Btw. To eliminate fuel as the issue, buy or ask the dealer to give you, a can of Motomix.


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[callan]

Ok, I'll check the cylinder, and I'll find some fuel with no ethanol. If neither of those get me anywhere, can I complete a pressure/vac test myself? I'm assuming it requires a special tool or machine.

 

[firefighterwolf]

Not getting enough fuel.

Dies when you hop on the throttle = too lean on the L adjustment.

Bogs in a cut = too lean on the H adjustment.

Undoubtedly the saw was adjusted at the factory to meet EPA requirements. Probably screams like a banshee at wide open throttle with no load.

 

[z71mike]

Ok, I'll check the cylinder, and I'll find some fuel with no ethanol. If neither of those get me anywhere, can I complete a pressure/vac test myself? I'm assuming it requires a special tool or machine.

Yes, special tool. For now, you can just have the shop do the test. Which they probably should have done already when you brought it there the first time. But you mentioned they were sub-par, so that's no surprise.

 

[AKDoug]

Not getting enough fuel.

Dies when you hop on the throttle = too lean on the L adjustment.

Bogs in a cut = too lean on the H adjustment.

Undoubtedly the saw was adjusted at the factory to meet EPA requirements. Probably screams like a banshee at wide open throttle with no load.

Remember that with high altitude and high temps the saw would run richer than the factory setting. Not to say it wasn't screwed up from the factory, but that should have been discovered during the tech's engine check.

 

[wilsonishere]

It sounds like you have a fuel tank vent issue. I would check it for defects or dirt plugging it up. I have fiddled with saws that have the same issue as yours and that was the culprit. It is often over looked and when not working has big consequences.

 

[callan]

Thanks wilson, I'll check that out too!

 

[firefighterwolf]

Remember that with high altitude and high temps the saw would run richer than the factory setting. Not to say it wasn't screwed up from the factory, but that should have been discovered during the tech's engine check.

Agreed...it will run richer at higher altitudes. However, the OP said that the saw was adjusted (presumably leaned out) to make up for that.

 

[AKDoug]

That's one of the hardest things to teach my customers. What's in tune today may not be right tomorrow, especially when we regularly see temps drop 40F in one day. Hence my enthusiasm for m-Tronic saws.

BTW OP, check and make sure your winter/summer shutter is in summer mode. I haven't seen it make that much difference but you never know.


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[Andyshine77]

Definitely vac/pressure test the saw, if you have an air leak the top end is likely not in the best shape. Did anyone remove the plastic limiter caps on the L and H for full adjustment? I've seen a few carbs where the screws would spin from vibration during use.