Fuel, air and spark...usually its fuel. After it shuts off check the float bowl. If it’s still full the pump and lines are probably working. It it’s not then it’s just burning off the bowl but having trouble staying full. If the fuel filter is dirty it may be allowing enough fuel to flow to fill the bowl on the starter but not enough to keep up with a running engine. Check the float valve and jets and also the air filter. Best of luck.
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