Author Topic: Ms 290 Walbro HD-18  (Read 177 times)

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Online jmester

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Ms 290 Walbro HD-18
« on: December 29, 2015, 08:05:01 pm »
Working on a 290. Rebuilt the carb. New fuel line. Press/vac passed. The saw runs all over the place. Won't hold a tune on the low side or the high side. I have to open the low speed like 2 turns to keep it running. Tried another carb and also another ignition module. Still the same. Went back and press/vac test and passed again. I checked the pop off pressure on both carbs and It was at like 30 psi and they still would not pop off. 30psi seems pretty high to me. I have heard that a high pop off can give you some hesitation coming off idle. Looking for some other opinions.
FEAR NO TREE. FEAR GOD.

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Online jmester

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Re: Ms 290 Walbro HD-18
« Reply #1 on: December 29, 2015, 11:03:56 pm »
Have been doing so reading about pop off pressure. Seems that a pop to high will cause some of the problems I have. Not holding a tune or not coming down smooth from full throttle. Think I will try and raise the inlet lever a little and reduce some spring tension and see what happens. Hope it will drop the pop some.

Higher pop = lean
Lower pop = rich
FEAR NO TREE. FEAR GOD.

Offline sharkey

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Re: Ms 290 Walbro HD-18
« Reply #2 on: December 30, 2015, 01:34:39 am »
I would raise the lever on that one.  It really isnt where it pops off, it is where it reseats that matters.  It should hold 5-7psi on the reseat and if it doesnt then the inlet seat needs polished.  It also seems to matter that the inlet needle is wet, so either try a little fuel or if the carb is off the saw take it over to the sink.   

Online jmester

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Re: Ms 290 Walbro HD-18
« Reply #3 on: December 30, 2015, 07:29:48 am »
 I will raise the lever(more fuel) a bit and see. But thinking about it now makes sense. Lever is low and causing the saw to be lean. Which would be why I had to have the low speed 2 turns out or more to keep it running.
FEAR NO TREE. FEAR GOD.

Online jmester

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Re: Ms 290 Walbro HD-18
« Reply #4 on: December 30, 2015, 09:29:24 pm »
Raised the inlet lever and still would not run right. Broke down and bought a new carb. Running good now. I have not had to buy a new carb in a long time.
FEAR NO TREE. FEAR GOD.

 

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