This happened to me last weekend on cyl #3. I hit all the jets I could see from the top of the carb (air box off) with compressed air & problem solved. Apparently the float was hanging like Mark said. I then put in a new fuel filter - NAPA Gold 3011 - just for good measure. It only takes a speck of dirt on a float needle to make it stick open. BTW, I had to blast the jets while it was running at idle - It wouldn't clean out properly when I did it shut off. Doesn't really make sense, I'm just sayin' what worked for me...