Stihl FS85RX Wont Rev

[24v6spd]

I have a Stihl FS85RX trimmer that will not rev, when you open the throttle it just bogs down. I have replaced the spark plug, fuel filter an air filter. I checked the muffler and spark arrestor to make sure they weren't plugged and tried adjusting the carb but nothing has solved the problem. I was thinking it could be the diaphram in the carb. Any suggestions on what could be causing this problem?

[Roger]

How old is the unit? Long service? Did the problem happen suddenly, or did it degrade over the course of time?

I formerly used an FS85 trimmer, currently use an FC85 stick edger. The FS85 had problems that sounded much like you describe, a problem that developed over the course of a couple of weeks.

I bought a carb rebuild kit and installed new diaphragms and gaskets. Problem solved. If you think the carb to be the problem and are unfamiliar with the diaphragm/gasket replacement procedure, PM me and I can provide you pics of how I did the rebuild.

[24v6spd]

How old is the unit? Long service? Did the problem happen suddenly, or did it degrade over the course of time?

I formerly used an FS85 trimmer, currently use an FC85 stick edger. The FS85 had problems that sounded much like you describe, a problem that developed over the course of a couple of weeks.

I bought a carb rebuild kit and installed new diaphragms and gaskets. Problem solved. If you think the carb to be the problem and are unfamiliar with the diaphragm/gasket replacement procedure, PM me and I can provide you pics of how I did the rebuild.
Thanks for the reply. I think the unit is about 4 years old. The problem developed just yesterday. I think I saw your pictures when I did a search of Stihl Fs85.