# Stihl 290 won't accelerate



## kenneth 3051 (Dec 13, 2008)

I have a stihl 290. 4 years old, medium use. It start fine runs ok until it warms up and then won't accerate. shortly afterwards it idle slow and dies.It will restart with choke and run until you let it go back to idle then won't take accerationany ideas would be appreciated. 
Kenneth


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## jaybird62 (Sep 28, 2006)

sounds like an obstruction in the carb. faulty diaphragm in carb. check the carb


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## kenneth 3051 (Dec 13, 2008)

*carb*

I have replace carb. with new carb. replaced gas with new mixed gas. replaced air and fuel filter, changed plug without any better results. I also felt for sure it was carb. thank 
Kenneth


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## justin3 (Apr 10, 2007)

Sounds like you have an air leak of some kind, when your engine warms up something is expanding and allowing air in. Check the condition of your fuel lines!


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## kenneth 3051 (Dec 13, 2008)

*fuel lines*

Thank you very much, I had been wondering about that. I just was dreading taking them out, or really installing others.Also wondering if coil or elcronic ignition coul be breaking down. Thank again i will repost if this fixes it.
Kenneth


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## paulr44 (Oct 14, 2008)

Yes, it could be the coil - an inline tester with an LED can help diagnose it. Since it dies at idle, I kind of doubt the ignition being the cause, but here are two such testers:

http://www.restockit.com/ragold/patton/In-Line-Spark-Tester-(MTN8709)

http://www.automotive-diagnostic-tools.com/Ignition-Spark-Tester-with-Adjustable-Gap-p/the404.htm

Does it have much spit-back out the carb. when running? If so, the piston skirt is worn.

Could be a crankcase leak - such as a crank seal etc.
Even the fuel tank vent can be an issue - if you can do a pressure / vacuum test on the crankcase it may help a lot. Kind of hard to do without a special intake block they make for just such a test, but the test tells you a lot.

2-strokes can be difficult to diagnose, as it's a whole different animal than a 4-stroke. The carb. has an impulse line to operate the fuel pump, and being a diaphragm style, has different properties in it. The entire crankcase is part of the intake system. The piston skirt is the intake valve.


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## kenneth 3051 (Dec 13, 2008)

*new ideas*

Thanks, Paul for some other Ideas and I definately will get one of the spark testers. 
Kenneth


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