Stihl MS290 down

[liquidskin]

I’m getting stumped with this saw, hopefully these symptoms sound familiar to someone...

Spent a few hours bucking on Saturday. Saw was running good, but at some point the saw would idle for only a few seconds between cuts and then die. If I gave it some throttle I could keep it alive. It was getting dark so I took it back to the garage for the night.

Next morning I figured a little maintenance couldn’t hurt. Pulled the spark plug and immediately noticed how loose it was. Cleaned it and tightened it. Cleaned air filter as well. Saw would just not start at this point. I replaced the plug, no dice. Took out the carb, sprayed it down. This seemed to help as I got it to start, but now it will only stay running if I’m at WOT. If I release the throttle it’ll die quick. No surging. So almost back to where I started, but more extreme.

Pulled the fuel line, no cracks. Next I’m going to try running it without the fuel filter in case the filter is suspect.

I’m a relative beginner with these saws so if someone has any other advice please let me know. Thanks!


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[salecker]

First thing to do is pull the muffler.
Look at the piston and see if it is nice and shiny with machine marks or is it rough and scored looking.

 

[liquidskin]

First thing to do is pull the muffler.
Look at the piston and see if it is nice and shiny with machine marks or is it rough and scored looking.

Will do and report back. Thanks


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[showrguy]

Will do and report back. Thanks


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Plan on getting new muffler bolts, they almost always snap..
Did you check impulse line also ??
If piston looks good, I'd plan on replacing fuel and impulse lines, and fuel filter..

 

[liquidskin]

Plan on getting new muffler bolts, they almost always snap..
Did you check impulse line also ??
If piston looks good, I'd plan on replacing fuel and impulse lines, and fuel filter..

Haven’t checked out the impulse line. I think I read that it’s tricky to access. Any tips?


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[showrguy]

Haven’t checked out the impulse line. I think I read that it’s tricky to access. Any tips?


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Sorry, I have'nt done much with the clamshell saws, but I know they can be difficult to work on..
There are better places for your questions though, but I'm not sure about posting that info here because of breaking some rule ??
Youtube is probably a good place to look also..

 

[tadmaz]

Muffler spark screen clogged?

 

[liquidskin]

Muffler spark screen clogged?

Will find out. Focus so far has been carb/fuel/spark


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[Angelo C]

I’m getting stumped with this saw, hopefully these symptoms sound familiar to someone...

Spent a few hours bucking on Saturday. Saw was running good, but at some point the saw would idle for only a few seconds between cuts and then die. If I gave it some throttle I could keep it alive. It was getting dark so I took it back to the garage for the night.

Next morning I figured a little maintenance couldn’t hurt. Pulled the spark plug and immediately noticed how loose it was. Cleaned it and tightened it. Cleaned air filter as well. Saw would just not start at this point. I replaced the plug, no dice. Took out the carb, sprayed it down. This seemed to help as I got it to start, but now it will only stay running if I’m at WOT. If I release the throttle it’ll die quick. No surging. So almost back to where I started, but more extreme.

Pulled the fuel line, no cracks. Next I’m going to try running it without the fuel filter in case the filter is suspect.

I’m a relative beginner with these saws so if someone has any other advice please let me know. Thanks!


Sent from my iPhone using Tapatalk

Are you familiar/can you tune the saw properly ?
where in NJ are you ?

 

[woodhog73]

First off forget the clogged spark arrestor screen. It will idle fine with a clogged screen. But it won’t run at high RPM because the exhaust can’t escape this effects back pressure and the intake ports won’t have vacuum to bring in fresh charge of air and gas.

Your problem sounds like a fuel issue. You say it runs idles then stalls. So I’m going to rule out a compression issue. Even if the piston and rings were worn and you had low compression, saw might still run but would be down on power through out the rev range. I’m also going to guess it’s not an air leak from a bad lower end gasket. Saw would have find compression and still run but would be lean so hesitant under load low on power, but
not stall when idling.

Since you replaced the spark plug, and said the impulse line is ok then Im gonna guess a gummed up carb.

Pretty common with saws that see ethanol and infrequent use ( not saying that is your saw just making a point )

Order a carb rebuild kit. Cheap and easy start there.

 

[liquidskin]

Doh. Well I decided to give the carb one more cleaning and realized I could have initially done a better job on the mesh screen filter. Got that thing spotless, little more compressed air in a few spots, reinstalled and bam, running. I guess I kind of appreciate now how sensitive these things are now. Glad to have figured it out though. Maybe muffler mod is next for me!


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