First, the low-pressure oil supply is not smooth. The inlet and return lines of the diesel engine from the tank to the injection chamber of the injection pump are all low pressure oil lines. When the pipe joints, gaskets and tubing in the diesel engine leak oil due to damage, the air will cause air resistance into the oil circuit. It will lead to poor oil supply, difficulty in starting the engine, slow acceleration, etc. In severe cases, it will automatically turn off the engine. When the tubing is aged, deformed and contaminated, the cross-sectional area of ​​the oil is reduced, or the oil is contaminated into the oil filter and the diesel filter element, the supply of fuel may be insufficient to reduce the engine power and make it difficult to start. When inspecting the fault, pump the oil to a certain pressure with the hand pump, loosen the gas screw. If there is a bubble overflow and the exhaust gas is always exhausted, it means that the oil passage is in the air; if there is no air bubble, but the diesel overflows from the bleeder screw, then there is no force. Indicates that the oil circuit is blocked. The troubleshooting method is to find out whether the damaged or aged gaskets, joints, or tubings are to be replaced. To prevent such failures, clean the oil filter and the diesel filter, check the piping, and solve the problem in time. Second, the oil pump piston spring breaks. When the engine suddenly shuts off during operation, it cannot be started. After the air is discharged and restarted, normal driving is resumed for a certain distance and the engine is automatically turned off again. It is very likely that the piston of the oil pump is broken. This fault removes the screw and can be eliminated by replacing the spring. Third, the oil pump check valve is not strict. After the engine has stopped and stopped for a certain period of time, it is difficult to start the engine. If the screw is loosened and the bleeder screw has an air bubble overflow, it must be re-discharged to start the air. This type of failure is mostly caused by the tightness of the oil pump check valve seal. The inspection method is to unscrew the oil delivery screw of the oil pump and fill the fuel oil chamber with the hand oil pump. If the oil level in the joint falls quickly within 3 minutes, the check valve seal is not good. Remove the check valve to check whether the sealing surface is intact, whether the check valve spring is broken or deformed, and whether particles are contaminated on the sealing seat surface. Take the grinding sealing surface, replace the check valve or the check valve spring to remove the fault. Fourth, high-pressure fuel pipe plugging. When a high-pressure fuel pipe of a certain cylinder is clogged due to deformation or impurities, there is a significant knocking sound at the oil pipe part after starting the engine, and engine power drop occurs because the cylinder does not work normally. The inspection method is to loosen the oil inlet nut of the high pressure oil pipe by cylinder, and when the sound of the knocking disappears after loosening a certain cylinder, it can be determined that the cylinder is a fault cylinder, and the fault can be eliminated after replacing the oil pipe. Fifth, the injector nozzle stuck. When the injector needle valve is stuck in the closed position, a regular knocking sound will occur because the pressure wave at the fuel injection pump hits the injector. The judgment method is to loosen the high-pressure fuel pipe connected to the fuel injector end. If the knocking sound disappears immediately, it can be concluded that the cylinder fuel injector needle valve is stuck.