Last season I had a problem with either the carb float sticking and/or the
needle valve sometimes not seating causing excess fuel to "dribble" into the
engine causing the symptoms you describe. I would then have to coax the revs
up and at the higher speed, that extra fuel was not a problem, and the
problem would resolve itself.

I was not that anxious to replace the float/needle valve last season so
thought I'd try something different. I installed a fuel shut off, and ran
the carb dry before storing (I removed the plugs and sprayed the fogging oil
directly into the cylinders and cranked over a few times). This spring
before firing it up, I sprayed carb cleaner into the carb fuel bowl via the
vent and let it sit for 5 minutes ... then started it up. So far no
problems, so here's hoping I won't have to work on the carburator at all.

Something I heard you might try, is install the fuel shut off (if you don't
already have one), and if it starts missing, shut off the fuel and run the
carb dry. Then tap on the carb (to free a stuck float/needle valve and
gently), then turn on the fuel and see if the problem is gone. I have a
mechanical fuel pump ... maybe if you have an electric pump, just pull the
fuse???

And if the problem goes, then I guess the decision would be to repair the
carb ... or not.


Recently the engine began to run rough, stumbling quite badly. This
happened
several times about twenty minutes out of port, trolling along in the
1200-1400 rpm range. Twice, I have then put the boat up on plane to scoot
home (3200-3400 rpm), only to find that half-way home the whole problem
disappears quite suddenly and dramatically, the engine smooths out, revs
pick up and I have to pull back on the throttle.