Hi, I recently purchased a (supposedly defect) Stihl FS 316 trimmer. I have not yet encountered the supposed problems (trimmer head would sometimes not get enough thrust), however I did encounter one problem; the trimmer head won't stop spinning when idling. It isn't spinning at full speed, so I don't think it is a problem with the gas cable. What could the issue(s) behind this problem be?
Try turning the idle speed down and see if it stops. If it doesn't stop then most likely the clutch is the issue. Had my personal Stihl brush cutter do that this summer. Issue was the weights on the clutch had rusted and were not retracting all the way to disengage the clutch. Had to disassemble the clutch and clean and lube the pivot points.
Make sure the throttle cable is not turned on the shaft, effectively shortening the throttle cable, causing the high idle and turning head. Whew...... Poor English at its best LOL.
