George wrote:
Stihl FS36 string trimmer. Walbro carb, diaphragm pump.

Sad story: starting last year, it would lose power after running for
15 mins or so. I could usually keep it going by nursing the throttle
for a while, after which it would return to normal power for a few
minutes, and then do they same thing again. This year, it did that
same thing the first time I ran it; but, after that, it would die
after running for about 30 seconds. I restarted OK, but then just
died again.

Spark seems OK, but I replaced the plug anyway. No help.

I got a carb rebuild kit, and replaced the filter, needle valve, and
the fuel pump and regulator diaphragms. This was a 'learning
experience', and didn't go that smoothly; but, I got it back to where
it would ... do the same thing - start, run 30 secs, die.

Then, I took out the high-speed adjust screw. (Not gummed up.)
Since then, it won't start. Alas.

The needle valve appears to be working: if I pump the primer bulb
with the regulator diaphragm removed, nothing comes up out of the
needle until I press on the actuator lever; when I do, fuel wells up
into the regulator chamber.

AFAICT, the regulator diaphragm is working: if I pump the primer with
the carb assembled, it gets fuel to the regulator chamber. And, if I
don't pump the primer, the regulator stays dry. However, I could be
confused about what I'm seeing, or how to interpret it.

Any suggestions would be appreciated.

Questions:
1. When I press the primer, should I see fuel squirt into the carb
throat? (I don't.)

2. Should I have (liquid) fuel sitting in the crankcase, after trying
to start it repeatedly? (I do.)

Thanks,
George

Get an electric?

I gave up on all those small gas powered devices long ago and never once
was sorry. Plug and play, no worries about starting or gas.

--
Joseph Meehan

Dia duit