[98Murray]

I have a Stihl FS45 weedeater that does not run correctly, it only runs with the choke
opened partialy. It will not run with the choke completely off, if i turn the choke off it reves too high and dies. I have adjusted the throttle all the way down, but it still reves too high with the choke off. How do i fix this problem?
Thanks for the help.

 

[echoman]

Sounds like a typical carb cleaning/rebuild is in order. Usually when a carb needs a kit, it will stall when opening the throttle or bog down under power(when using) as the pump diaphram gets brittle and cannot supply enough fuel through engine vacuum. You said it "revs high"? Depending on how high, it could be pulling more fuel through the high speed circuit because the low is blocked or there is an air leak somewhere causing a lean surge. Usually most small 2 stroke engines need to see many hours of use or sit idle for many years of non-use before seals need replacing, if ever. This model, unless heavily used should not exhibit worn seals as the cause in my opinion.

 

[GTP]

Have you tried adjusting the carb? Sounds lean. The reving and dying is it going lean racing up using all the gas and dying. It "runs" on choke because it's barely getting enough gas to keep it running by closing off the main venturi.

1. Try locating and turning the "H" needle on the carb counterclockwise about 1/4 turn and try it then.
2. Keep going counter clockwise with the needle until it runs at full throttle...

3. once you have it running strong at full throttle hold the throttle on full and slowly turn the H needle counterclockwis until it 4 stroke or slows and runs rough.

4. slowly turn the H needle clockwise about 1/32" of a turn until it smoothes a bit ...this should be a good place to leave it

As Echo mentioned you may want to order a rebuild kit ($8-$10) with shipping (www.mowers4u.com) and install it...you tube has a great few vids on rebuilding diaphragm carbs. The same tuning applies above once you've re-built the carb.

George

 

[98Murray]

thanks for the help. I drained the old gas and put in fresh gas oil mix and it runs good now. I think there was to much oil in the gas

 

[GTP]

thanks for the help. I drained the old gas and put in fresh gas oil mix and it runs good now. I think there was to much oil in the gas

Or coagulated ethanol