Thread: stihl MS 290

Can anybody help with this problem.Saw starts first pull.Full power on acceleration ,idles fine. After about 3 - 5 mins of work engine will not produce full power.Changes crankshaft seals,exchanged carb, checked fuel lines. Let motor cool and cycle repeats itself never getting better or worse.Also removed spark arrestor from muffler.

Sounds basic but did you check the air filters? How about the fuel filter in the tank? Have you tried running it with the choke on making the mixture rich? That would at least give you direction if the carb is clogged. Maybe the spark plug? I've found in the past the simplest issues are what make the biggest headaches.

Mine did the same thing. I took it to a dealer and they found that the fuel did something to the material that the fuel line was made of and when you gave it the gas the line would collapse. They put a new line on it and everything works good now.

How could I forget! Mine did the exact same thing on a 026.

Sounds like the impulse line to me. Or a fleck of gunk in the impulse line input to the carb. I'd pull the carb and check the impulse line. My 210 ran the same and I could not figure it out, 'till I read a post by Lakeside and pulled the impulse like. It was rigid from age and not sealing right. New impulse line did the trick. Also tighten the carb bolts good and snug and check that the carb seal is OK (it can leak where it connects to the impulse line).

Also could be the coil. Not very common, but sometimes they go out, expecially when they get hot. Lastly check that the piston and cylinder are not scored.