Unscrew the carburetor into the pipe joints, pick up the petrol pump with your fingers to the force arm position, slowly turn the engine crankshaft, so that the hand arm to and fro to walk a work schedule. If the trip is small, the gasoline pump can be moved to the maximum working stroke (camshaft eccentric eccentric maximum Department at the top of the rocker arm), and then force the hook arm, you should feel a little reserve trip. If there is no itinerary, the gasket on the joint surface between the pump body and the engine is too thin. If the stroke is too large, it indicates that the gasket is too thick or the inner arm is worn and should be adjusted or repaired. If the rocker is working properly, you can remove the fuel pump inlet and outlet joints, with finger blocking the inlet, pull the hand arm, the fingers should feel attractive; pull steady, if you feel the suction can maintain 5S Above, you may determine that the valve is good; pull the hand crank and then block the oil outlet, according to the feeling of pressure on the inlet valve to determine. If the valve is not tight, it should be demolished to replace the oil valve. When the fuel pump outlet out of power, you should check the fuel pump into the gas pipeline and gasoline filter situation. When the pipeline or filter is clogged or the pipeline leaks, it will also result in the problem of weak or no oil. If the gasoline pump test function is normal, you do not have to disassemble and check, only do a good job of cleaning.