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Stihl only idle

#1

C

clinct

Have a 2 year old Stihl FS55 trimmer that starts and runs fine at idle. Problem is it will not rev without bogging out and stopping. I have changed fuel, changed plug, removed fuel filter, checked for leaking fuel lines, verified spark screen is not plugged, and tore down carburetor to clean, and also soaked in carb cleaner overnight. Yes there was oil in the gas :smile:, and the mechanicals are almost like new. If it press the prime bulb while at idle it revs high for a few seconds so I assume the coil is OK. Carb is a zama C1Q-S97 which will cost me ~ 75.00 to replace, rebuild kit ~ 20.00. Any suggestions, should I get a rebuild kit and see what may be lodged under the welsh plug痴 and replace the insides (which all look fine to me) or toss the trimmer and get a replacement?


#2

rekees

rekees

I would take it to a Stihl dealer and have them check it. A Stihl trimmer that new shouldn't be worn out yet. My trimmer bogs out when the head gets fouled with weeds. Too much of a load for the engine. Is it possible there is something causing the head to bind up or could the shaft be bent? Have you tried to rev it up without the head?


#3

D

dcgrazier

I read all of the things you did to the engine, but I did not read that you tried adjusting the carburetor settings. I have to tweek my Stihl from time to time.

Dave G


#4

BKBrown

BKBrown

I believe in another thread someone said to check the shaft and head to see if they are free - sounds like maybe when the clutch engages it is not allowing the engine to rev. ?????????


#5

essasmallengines

essasmallengines

I think you should go at the carb again, it could me the main jet is blocked, but the Idle port is ok because you do idle.


#6

R

rockytop

You might try adjusting the Hi Lo adjusters. with a small screw driver or the newer adjusting tool screw them both in till they touch bottom, DO NOT FORCE them beyond just touching the bottom of the seat. back the Lo out three quarters of a turn. back the Hi out one and a half to two turns,

start it up and adjust from there. on both of them but this will get you in the game.
good luck:thumbsup:


#7

BKBrown

BKBrown

From another thread -- it might be clogged or blocked muffler or spark arrestor -- (back pressure creates a problem) check and clean muffler and arrestor -- Might help !!!! Good Luck !


#8

M

meguell3

Look, I dont have any idea how old this post is but if none of the other things work I can get you a new carb for 40.00 and that includes shipping. Private message me if youre interested.
clinct said:
Have a 2 year old Stihl FS55 trimmer that starts and runs fine at idle. Problem is it will not rev without bogging out and stopping. I have changed fuel, changed plug, removed fuel filter, checked for leaking fuel lines, verified spark screen is not plugged, and tore down carburetor to clean, and also soaked in carb cleaner overnight. Yes there was oil in the gas :smile:, and the mechanicals are almost like new. If it press the prime bulb while at idle it revs high for a few seconds so I assume the coil is OK. Carb is a zama C1Q-S97 which will cost me ~ 75.00 to replace, rebuild kit ~ 20.00. Any suggestions, should I get a rebuild kit and see what may be lodged under the welsh plug痴 and replace the insides (which all look fine to me) or toss the trimmer and get a replacement?
Click to expand...


#9

J

jteuban

Don't waste ur money by taking it to the dealer the prob is simple take out the spark arrested screen out of the muffler and clean out all the crap until you can see through it good. I have seen this problem MANY times. once you take it out, start your trimmer again and your problem should be fixed. If you have a bench grinder with a brush works well cleaning it out. Good luck with it. Should be a 15 mm bolt. Cheers


#10

Briana

Briana

Hello, I moved your thread to the new Stihl Forum. :smile:


#11

Z

zark

I dont know if the trimmer has a spark arrestor screen or not. But I had an MS 181 chain saw for brush cutting, etc. It would sit for some periods of time at idle while I stacked, chipped, etc. This would clog the screen every couple days of use. Would idle great and bog when trying to cut, clean the screen and it would run like new. Sure does sound like the problem?


#12

D

DaveTN

Usually when I find a weedeater or chainsaw that will idle, but won't throttle up, first thing I do is turn the LOW side counter-clockwise to enrichen it. Turn about 1/16th turn, then check for throttle up. If it improves some then do another 1/16 turn, and repeat until it throttles up OK. Then I go to the HIGH side and hold the throttle about 1/2 to 3/4 open and adjust the HIGH side until the engine revs at its best RPM. Then STOP. If it still stumbles and won't throttle up, I'd take the carburetor cover plates off and check the diaphragms. Spray them out, clean the carburetor with spray etc. and replace them in order removed. That usually does the trick!


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