# Sthil FS55 Trimmer Carb Problem



## doublea (Aug 16, 2010)

I'm having a problem with a Sthil trimmer carb. Runs on low side but won't open up. I cleaned everything thoroughly; diaphragms look good; jets are clean; removed, cleaned and adjusted needle valve.
This model only has one adj. screw. Doesn't matter much where you set it, it still does the same thing. I removed fuel return hose while it's running and I'm not getting any fuel out; looks like low pressure? I already put new hoses and cleaned fuel filter. Am I missing something or is it time to buy a carburator kit?


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## geogrubb (Jul 28, 2006)

doublea said:


> I'm having a problem with a Sthil trimmer carb. Runs on low side but won't open up. I cleaned everything thoroughly; diaphragms look good; jets are clean; removed, cleaned and adjusted needle valve.
> This model only has one adj. screw. Doesn't matter much where you set it, it still does the same thing. I removed fuel return hose while it's running and I'm not getting any fuel out; looks like low pressure? I already put new hoses and cleaned fuel filter. Am I missing something or is it time to buy a carburator kit?


While it is running spray, using the straw, some carb/brake parts cleaner behind the carb and along all mating surfaces to see if the engine tempo changes, if it does you have an air leak and can fix it, if not.
Put a new diaphgram kit in it, blow out all the holes cracks and crevases with brake parts cleaner, i suggest using the old metering arm unless it was very worn as it has the proper height setting. Have a good one. Geo


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## doublea (Aug 16, 2010)

*Not carb at all*

Thanks Geo but the kit didn't fix it. I put everything new in the carb..
Here's the hint that helped me finally figure it out. "When I turn the engine off I hear a little squeal from the clutch area as it spins down". 
I had to replace the throttle cable a few days ago and when I reinstalled the two screws in the middle of the plastic shroud, I switched the long and short screws. I realized my mistake when the shaft wouldn't turn and switched the screws back to the correct location but too late - I had damaged the shaft making in not turn as freely as it should. So now when it tries to rev and the clutch tries to spin the shaft, there is too much resistance. It finally dawned on me after I thought about it awhile. Live and learn. Thanks again


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