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View Full Version : Stihl trimmer runs without squeezing trigger


tinman
05-10-2005, 10:49 PM
Any way to easily fix this.... Tried the "idle screw on back of trimmer" to no avail. Does not run wide open, but about 70% . Makes it hard to delicately trim arounf plants, fences, etc.

Trimmer is a Stihl FS 80 I beleive. Thanks

mike76
05-10-2005, 10:58 PM
You need to check the muffler screen to see if its stopped up. Check to fuel lines to see if they have a split or are dry rotted. Try this and see if this works for you, good luck..

tinman
05-10-2005, 11:01 PM
You need to check the muffler screen to see if its stopped up. Check to fuel lines to see if they have a split or are dry rotted. Try this and see if this works for you, good luck..
No,,,I'm sorry.... It runs fine... the problem is the head spins too fast without squeezing the trigger. Like the throttle is stuck.

dvmcmrhp52
05-10-2005, 11:05 PM
No,,,I'm sorry.... It runs fine... the problem is the head spins too fast without squeezing the trigger. Like the throttle is stuck.



When's the last time the air filter was replaced?
Sounds like the engine needs air or the low idle screw is way out of wack............

mike76
05-10-2005, 11:09 PM
Sorry i misunderstud, Undo the throttle cable and see if the trimmer idles and if it does them you need to check the cable.

dvmcmrhp52
05-10-2005, 11:12 PM
Sorry i misunderstud, Undo the throttle cable and see if the trimmer idles and if it does them you need to check the cable.




Could be the handle on the shaft that the cable goes to has moved and stretched the cable too tight...............

tinman
05-10-2005, 11:12 PM
Sorry i misunderstud, Undo the throttle cable and see if the trimmer idles and if it does them you need to check the cable.
Will try that...Thanks

When's the last time the air filter was replaced?
Sounds like the engine needs air or the low idle screw is way out of wack............

Replaced air filter last year

mdmowerman
05-11-2005, 07:18 AM
clutch gone bad? same thing here,about 150 to fix, might be worth a new one, your call.

Gautreaux's LNG
05-11-2005, 10:22 AM
Check the throttle cable for not being in the correct place. for some reason the cable is pulled to keep the throttle open position. It may have moved out of the holder for the metal end causing this condition. disconnect the cable from the carb. If the trimmer still runs higher than normal its in the carb. If it runs ok and you can manually control the speed with your hand the cable is caught or out of the correct place. Good Luck

ed2hess
05-12-2005, 11:20 PM
Check the throttle cable for not being in the correct place. for some reason the cable is pulled to keep the throttle open position. It may have moved out of the holder for the metal end causing this condition. disconnect the cable from the carb. If the trimmer still runs higher than normal its in the carb. If it runs ok and you can manually control the speed with your hand the cable is caught or out of the correct place. Good Luck
The problem is likely in the throttle cable adjustment not the idle adjustment on the carb. If there gets too much slack the little bullet on the end of the cable can get out its hole in a carb actuating arm and the unit wil run fast. Get it back in and adjust the cable screw for no play when the throttle lever is not operated, so the bullet can't get out!

dh500
05-13-2005, 06:07 AM
A mate of mine had a problem with a 2 stroke motor that would not run slow, even with throttle closed. Turned out that air was leaking past shaft seal.

dh500