The fuel injection pump works for a period of time. By checking the sealing condition of the oil outlet valve, the wear of the plunger and the working condition of the oil pump can be roughly judged, thereby facilitating the determination of repair and maintenance methods. When inspecting, unscrew the high-pressure oil pipe joint of each cylinder and pump the oil with the hand oil pump of the oil pump. When the oil pipe joint of the fuel injection pump is found to have oil flowing out, it indicates that the oil discharge valve is poorly sealed (of course, if the oil discharge valve spring is broken) This happens. If there is a poor sealing phenomenon in the multi-cylinder, the fuel injection pump should be thoroughly adjusted and replaced, and the replacement parts should be replaced.