Accepted Answer

Hi and thanks for using justAnswer.com.
Sounds like the pingpong ball in the gas tank trick. Running the pickup tube suction draws the ball to block flow. Shut down and it floats free. Then starts fine again. In your lawn mower you have a pickup tube with a screen. The screen could be picking up sediment, then releasing it on shutdown. More likely you have sediment in the carb bowl and it is being sucked into the float valve. Drop the carb bowl and clean the bowl & float pin with gas- NOT carb cleaner. Carb cleaner will destroy rubber gasket rings in a lawnmower carb.
I hope that this information was helpful to you. If it was please remember to click "ACCEPT" on your screen to make sure that I am paid for my efforts. By clicking ACCEPT you are not giving up your ability to ask more questions pertaining to this subject, and I will be happy to respond to these as well. Please take a moment and leave feedback, it is very important!

Expert:	Stephen Cutler
Pos. Feedback:	99.3 %
Accepts:
Answered:	8/24/2009

General C&ontractor

35 years of troubleshooting construction, remodel, component & material failures. What to do next