Working on a Stihl FS90R (4-mix) may start great for several days, then decide to not start. After 20-50 pulls, it'll start, then usually start great for the rest of the day, maybe several days, then hard to start again--all of this according to owner. I adjusted valves, a little too wide but not much. Checked muffler! Got it to start after numerous pulls, runs great, restarts great. I checked spark when it was not starting--seems to be okay. This trimmer is maybe 4 years old, used on...
Stihl FS90R, Starting Problems
Stihl FS90R, Starting Problems