Sounds like a B&S. Poorly made old tech motors. The carbs are the worse
problems. Full of diaphrams that warp and don't work well.
It is probably dirt or a diaphram driven valve that is bad from dire in
the gas. Try a good cleaning job first. I hope that helps.
Also in the future, add an inline filter if possible. High test gas also
helps keep carbs clean.

JJ

Bruce wrote:

I have a lawn mower with a Briggs & Stratton 5HP Quantum I/C engine
that suddenly developed problems. It's run great for the several
years that I have had the mower (bought it used) and the engine has
been well maintained during that period of time (regular oil/air
filter changes, stored inside and out of the weather).

Last Saturday, while cutting grass, the engine stalled. Each time I
pulled the cord and it would start immediately but quickly stall
(within a few seconds). This engine has a little rubber primer bulb
on the fuel tank that you can use to squirt a little gas into the carb
for a cold start. When I pressed the bulb repeatedly right after the
engine started and began to stall, the engine received enough fuel to
keep running for a few seconds. When I stopped pressing the primer,
it soon stalled.

At first I suspected that the main fuel line was blocked so I took the
air filter and holder off and detached the fuel line from the gas tank
(the primer bulb has a smaller, separate line that goes from it to the
carb). Fuel flowed easily from the tank through the nipple where the
main line attaches. Next I blew some compressed air into the fuel line
and a nice vapor of gas mist exited from the orifice in the carb. I
took the opportunity to blow out the air filter and pre-cleaner screen
(somewhat dirty but not too bad).

I put everything back together but the problem continues -- same
symptoms as before. Anyone have any ideas? I don't know squat about
small engine carburators (or engines for that matter) but would love
to fix this without a trip to the shop.

- Bruce
rbloth at yahoo dom com

PS ... In case anyone needs it here's the model/type/code for the B&S
engine:

126802-3423-01 92111658