Dear Gents,
My (formerly) trusty-ol� Stihl FS36 has recently developed the habit of dying at low RPM after several minutes of operation (which presumably indicates that the problem is somehow temperature-related�).
The unit is quite happy after first start-up, and I don�t sit on �choke� for any more than a couple of seconds, even though I�ve got both the high and low needles set to fairly lean mixtures. I don�t normally run it at any more than mid-range RPM, so even after the ten minutes or so at which the problem starts to occur, the motor still wouldn�t be terribly warm (especially in this weather�) Once the problem does start, the unit will still run strongly if I maintain high RPM, but if I let the revs drop too much, it will either immediately die, or start �hunting� around a bit before eventually dying anyway. Restarting never seems to be terribly difficult, even when the problem is in full swing, but if I don't give it full throttle at such times, it just dies again...
My own thoughts are that it�s no longer possible for the problem to be caused by something like gummed-up carburettor jets, because my first reaction was to pull the carby apart and to clean it to within an inch of its life (including the little gauze filter-screen), to no avail. For what it's worth, the carb itself is a Walbro WT160B, and I replaced both the pump and the metering diaghragms only a couple of years ago.
As regards the possibility that the breather-valve for the fuel-tank is clogged up, I�ve also given that a clean, as well as removed the fuel-cap momentarily when the problem has started to occur, with no improvement resulting.
Might any of you happen to know whether there are any known temperature/age-related Ignition Module faults that are endemic to this model, or have any of you had a similar problem that has gone away after they tried replacing/swapping the Ignition Module? Going by the following (unfortunately inconclusive) thread, I don't think my unit's problem is an isolated one:
https://www.outdoorking-forum.com.au/forum/ubbthreads.php/topics/712/Stihl_FS_36.htmlMany Thanks in advance,
Moby Mick.
