MS290 hunting idle

[RED-85-Z51]

Got a very low use 290 in that has me a bit puzzled, starts on 3 pulls and runs great, loads of power and holds a solid 12,700 rpms up top consistently. It actually idles decent until you move it around, then the chain will spin for a couple seconds. Idle will hunt some. I sprayed brake cleaner at the clutch side seal and carefully behind the flywheel...didnt change anything with the idle. Sprayed around the intake and base...no change. I put on a new carb and it made it as good as it is now...a bit better than when it came in...which was not wanting to idle at all.

I took my mityvac ona job last week and someone relieved me of it off my tailgate...so i can't pressure or vac test it yet. But..normally brake clean will cause something if there is a problem.

Thoughts?

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[Alphadelta]

Got a very low use 290 in that has me a bit puzzled, starts on 3 pulls and runs great, loads of power and holds a solid 12,700 rpms up top consistently. It actually idles decent until you move it around, then the chain will spin for a couple seconds. Idle will hunt some. I sprayed brake cleaner at the clutch side seal and carefully behind the flywheel...didnt change anything with the idle. Sprayed around the intake and base...no change. I put on a new carb and it made it as good as it is now...a bit better than when it came in...which was not wanting to idle at all.

I took my mityvac ona job last week and someone relieved me of it off my tailgate...so i can't pressure or vac test it yet. But..normally brake clean will cause something if there is a problem.

Thoughts?

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Still new to saws so I am guessing a little - but is it possible maybe the exhaust is fowled and causing some issues? My only other thought is a small leak around the base of the cylinder, but I have a sneaking feeling that is a very low chance of being an issue.

When I have idle issues I almost always end up focusing on the carburetor.

 

[PV Hiker]

Fuel filter defective?

 

[RED-85-Z51]

Still new to saws so I am guessing a little - but is it possible maybe the exhaust is fowled and causing some issues? My only other thought is a small leak around the base of the cylinder, but I have a sneaking feeling that is a very low chance of being an issue.

When I have idle issues I almost always end up focusing on the carburetor.

That was my thought, on the carb...and that fixed the majority of the idle problems. It no longer stalls out or revs up high on its own.

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[RED-85-Z51]

Fuel filter defective?

Ill put one in, i usually see filter problems show up as a high speed starvation but...cheap part to try

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[Arrowhead]

Check impulse line and fuel line.

 

[Alphadelta]

That was my thought, on the carb...and that fixed the majority of the idle problems. It no longer stalls out or revs up high on its own.

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If you can I would maybe clean both carbs really well, I have an Ultrasonic cleaner and it works wonders on carbs. While you're on cheap parts, like what Arrowhead said, def check your fuel and impulse lines.

 

[RED-85-Z51]

Fuel line is good, didnt pull the handle to look at the impulse line yet.

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[PV Hiker]

Meanwhile out in left field.... Slightly loose wire in the ignition system or inside the spark plug boot. You did say it idles wired when you move it around...

 

[SEAM]

Fuel filter stuck somewhere in a tank corner? The tank vent might be another possibility...

 

[Alphadelta]

Fuel filter stuck somewhere in a tank corner? The tank vent might be another possibility...

Second that thought as well, pretty sure the vent for 250 is on its way, it likes to lock up, which results with a quick turn of the cap to vent the tank and then it runs fine, but until I do that it hunts a little before it dies.

 

[RED-85-Z51]

Pulled it apart, found a tiny crack in the bellow of the intake boot.

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