# Stihl FS 80 won't run at open throttle. ??



## johnssoftail (Jul 8, 2009)

Hi every one, I have a question regarding my FS80 string trimmer.It starts easily and idles good, however, when I open the throttle it falls on its face. I have replaced the plug, cleaned the filter in the tank and the air filter with no luck. If I close the choke nearly all the way it will rev up. The problem started after I ran it out of gas. it hasn't ran right since. Any help would be appreciated.

Thanks
John


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## Rentahusband (Aug 25, 2008)

Try adjusting the H speed mixture screw on the carb. Turn the screw all the way in (carefully) until seated. Initial setting is aproximatly 1 turn from seated posisition. Fine tune it from there until it runs properly. If that does not help then the carb may need attention.
Dean


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## rotti1968 (Apr 26, 2009)

Sounds to me its going to be a carburetor thats in need of a good cleaning and rebuild or replacement. This is I would say the # 1 reason that most of our stihl products are brought in for service in our shop/dealership.


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## geogrubb (Jul 28, 2006)

johnssoftail said:


> Hi every one, I have a question regarding my FS80 string trimmer.It starts easily and idles good, however, when I open the throttle it falls on its face. I have replaced the plug, cleaned the filter in the tank and the air filter with no luck. If I close the choke nearly all the way it will rev up. The problem started after I ran it out of gas. it hasn't ran right since. Any help would be appreciated.
> 
> Thanks
> John


If it boggs when you open the thottle but you can nurse it to open throttle then open the LO until it no longer boggs(if you have a Lo).
If you only have a Hi start by opening it by about 1/8 to 1/4 turn.
If you have neither it will be necessary to remove and clean the carb and probably install a new kit, when installing the new kit, use the old metering arm unless the old one is very worn, as it has the proper height setting. Have a good one. Geo


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