Sounds normal for an engine not getting enough gas. It will indeed run with
very little throttle opening. The choke opening is just as small - so what
you're seeing with your thumb isn't much smaller than what it gets at full
The inlet needle should begin to admit fuel before the float reaches the end
of its travel. Something blocking it will produce the symptoms you
Some inlet needles have elastomeric tips, which can swell or fall off. Be
aware too that many small engines nowadays use a TINY rubber seat with a
steel needle. You might not expect it to be there, and the rubber seat
might not be very visible till your air gun blows that seat into the
neighbor's yard. Then will definitely have to go get another one. It might
be sticky or hard or broken and blocking the passage too.
I'd try a good off-the-engine carb cleaning before much else, and I'd just
go buy a carb kit to get new gaskets and a new needle and seat before even
starting. Personally I've had very mixed results with on-the-engine carb
From: Arvid Jedlicka
Subject: [Shop-talk] Need some thoughts an a snow blower that will not run
He had sprayed carb cleaner down the throat of the carb and had removed the
float bowl. While I was there we removed the idle and main jet adjustments
and used the straw of the carb cleaner to shoot cleaner thru the internals.
We then checked the float level and when hanging freely fuel flows quite
nicely from the tank, when the seam on the float it horizontal ... or
parallel with the bowl base the fuel stops and does not start again as the
float reaches the end of it travel. So we feel the fuel system up to the
float in the bowl is working correctly.
We put it all back together and tired it and zero, zilch, nothing. On a whim
I stuck my thumb over the throat of the carb and blocked off 95% of the
opening. When I did so it actually started and would run as long as my thumb
was there. This really surprised me because the opening to the throat of the
carb was so small I didn't think enough air would get in for any combustion
to take place.
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