STIHL 362 bogs, may not be getting to FULL RPM's

[schreib69]

My Stihl 362 (not M tronic) has some high end runnability problem. Looking for suggestions as to possible things to check.
-- spark plug is tan but wet all over the tip when cold: Electrode, ceramic and threads
-- spark plug is tan but DRY when engine hot, but wet around the threads.
Question: Are both conditions "normal"?

-- During start up / warming the engine hesitates a bit during high speed throttle pushes, even seems like it won't hold a steady RPM just after start when the throttle mechanism is holding it at high revs before I blip the throttle to let it idle down.
-- It takes a minute or two to warm and then, generally, it seems to run up to FULL throttle OK. However, not knowing how high max RPM "sounds" it just "seems" it is not reaching full RPMs. I have an RPM meter, cheap one, but have never tried it. . . I do not know what RPM the 362 is specified at for top end RPMs.

It is not the gas age or the quality-- installed all new this spring and it did this same thing last year-- 91 octane ethanol free.
-- Last week the saw bogged down making a felling cut while running horizontal, pulled it out and cut horizontal on a felled log and it seemed to do better, Does not do this now. . . Sometimes it just bogs down in the middle of a 10" wide log and I am forced to pull weight of saw up off the log to allow it to regain RPM and restart the cut. Just providing more info to aid in symptom info.

Question: Could it be my engine is "worn" enough that I have less than full compression and could better use a hotter plug or something along those lines? or slightly less oil in the mix? or not getting all the spark power to the plug somehow?
Thanks for your pointers up front!

 

[merc_man]

Start with new plug maybe.
Possible air leak sonewhere

Sent from my SM-G950W using Tapatalk

 

[Shane¹]

I had a 362 that the carb diaphragms got hard then it didn't want to run right may not hurt to rebuild the carb

 

[Pincher]

Welcome to the forum. nice to see more locals.

 

[stihl livin]

Fuel filter or line? Maybe some history on the saw.

 

[schreib69]

I was reading over the manual and noticed a section regarding the winter / summer carb preheat port. This sliding port was in the SUMMER setting. Per the manual it is important that it be flipped to winter below 50°F and back to SUMMER above 70°F. Based on my recollection of the temps(30's up to 50's) these last weeks it seems this is the likely culprit.

Thanks for all your input folks. I will still keep it all in mind . . .

 

[merc_man]

I think its more then just you winter /summer mode. I have forgot to switch mine befor and never had any issues.
If you dont have a pressure vac tester may ne a good idea to have that cheacked by dealer to be on the safe side. I thouht I read on your one post that when you cut on the side it ran worse? That ther is a sign of bad seals.

Sent from my SM-G950W using Tapatalk

 

[stihl livin]

I think its more then just you winter /summer mode. I have forgot to switch mine befor and never had any issues.
If you dont have a pressure vac tester may ne a good idea to have that cheacked by dealer to be on the safe side. I thouht I read on your one post that when you cut on the side it ran worse? That ther is a sign of bad seals.

Sent from my SM-G950W using Tapatalk

I never switched it on the 361 I had between seasons and had no issues.

 

[schreib69]

I never switched it on the 361 I had between seasons and had no issues.

Interesting. The problem may be I will forget to test this out next winter when it again finally becomes cold enough!

I envy your 361. Used my neighbors way back and that was the reason I got a 362, figured it would be at least as good as the 361, but it does not "seem" to be!

 

[Redfin]

Try running saw without air filter. Report back.

Have you trued tuning the saw?

 

[schreib69]

Try running saw without air filter. Report back.

Have you trued tuning the saw?

-- 1st thing I did was pull the air filter and start it-- no effect, same problem
-- 2nd thing I pulled the plug, saw it wet, re-installed and ran till hot, removed and rechecked and saw it was dry. Images show these two events.
-- no other "tuning". My belief here is that smooth accel. should happen regardless of high or low needle positions, but that is wrong probably. . . open to tuning suggestions on the carb!
-- So, I am reading you are not believing the SUMMER port selection means much when under 50°F as manual implies? Correct? or are you just not addressing that point?

 

[Pincher]

Is there any chance you can duplicate the problem? The symptoms of bogging down while horizontal could be as simple as the fuel filter being hung up if fuel tank wasn't half full or better. But you state if you cut on a felled log horizontally it ran better. Did you mean vertically? Symptoms would indicate a lack of fuel. Not sure how the tank vents on that model but it would be easy to check if symptom arises, open the fuel cap and see if it runs better.
There are several good you tube videos on how to tune a carb. Once you learn what to listen for, a tachometer is almost unnecessary.

 

[schreib69]

Is there any chance you can duplicate the problem? The symptoms of bogging down while horizontal could be as simple as the fuel filter being hung up if fuel tank wasn't half full or better. But you state if you cut on a felled log horizontally it ran better. Did you mean vertically? Symptoms would indicate a lack of fuel. Not sure how the tank vents on that model but it would be easy to check if symptom arises, open the fuel cap and see if it runs better.
There are several good you tube videos on how to tune a carb. Once you learn what to listen for, a tachometer is almost unnecessary.

No can not duplicate now. As a kind of final test before posting I went out one day to attempt this, it was warmer:
-- initially, first minute or so it hesitated a bit, say about 9 am.
-- then, I revved her up and she screamed like a raped ape; I cut through two tanks of gas with not a hiccup; I don't believe I did any cutting like a FELLING cut though(turn saw 90° from upright, cut the wedge and back-cut on a vertical tree). All downed trees.
This is why I so readily was convinced on my own that the winter / summer port was the culprit.
So, your suggestions certainly make sense but after running like this. . . nothing to test against. I was really convinced it was hesitating due to lack of fuel because of intermittent particles catching in the high speed fuel circuit but am now convinced it was not fuel but AIR limited causing hesitation. . .
Thanks, just the same.

 

[Redfin]

-- 1st thing I did was pull the air filter and start it-- no effect, same problem
-- 2nd thing I pulled the plug, saw it wet, re-installed and ran till hot, removed and rechecked and saw it was dry. Images show these two events.
-- no other "tuning". My belief here is that smooth accel. should happen regardless of high or low needle positions, but that is wrong probably. . . open to tuning suggestions on the carb!
-- So, I am reading you are not believing the SUMMER port selection means much when under 50°F as manual implies? Correct? or are you just not addressing that point?

Was the saw running well the last time you used it? What was temp? Tuning is an absolute at wide temp swings. Strato saws like the 362 need more fuel to run at their peak.

Open the L a tad to see if the stumble off idle goes away. More fuel on H screw wont hurt either.

And dont worry about the carb shutter. It really needs to be frigid to have the carb ice up, thats what the shutter is for, to allow warm air into carb box.

 

[Dustin4185]

Where I am at, I chuck the shutter. Sounds like a carb issue or possible air leak. I would replace plug, check the tune/retune after watching some videos. Keep in mind if your limiters are intact, you won’t be able to close the needles all the way to start at “0”. How old is the saw? Have you tried a different bar/chain? I’ve had a friends saw act similar that wound up being a very tight spot on the bar causing low power like issues. If you aren’t confident in tuning or diagnosing the problem, find someone that is. Not trying to be a smart a$$, but it’s not worth burning up a saw if it is something simple. My dealer actually will show people how to tune a saw.

 

[mainer_in_ak]

Had this same problem on a few saws running made in russia and made in china bosch spark plugs.

I run made in japan desnso spark plugs of equivelent heat range. Could beas simple as a new spark plug

Youre running a good spark plug though, so who can say? At least your 362 isnt all hopped up on m-tronic chronic. So should be purdy easy to fix.