Tap on the side of the bowl with a screwdriver handle. This will remedy sometimes. If that doesnt work, take the carb off and flip it upside down. Blow in the gas line. It should not let any air in, if it does your needle/seat has crap in it, is worn out, or your float is WAY out of whack. Take the float/needle/seat apart and give a thorough cleaning with carb cleaner and blow it out with compressed air, if you have it. I hope this helps