Q: what are the reasons for the bad start of diesel engines? How should we quickly diagnose the starting faults of ordinary diesel vehicles? Answer: we can quickly diagnose the cause of the fault from three aspects: first, to see if there is a sound of explosion when the diesel engine starts, and whether there is smoke coming out of the exhaust pipe. If there is no sound and smoke, it means that there is no diesel oil entering the cylinder at all. It is necessary to find out the cause of diesel transportation. The two is to hear the occasional eruption, the exhaust pipe has smoke, no matter how much the fuel has entered the cylinder, but it can not complete the normal combustion process. This situation needs to find out the causes from the timing of oil supply, the quality of fuel injection atomization and the temperature and pressure at the end of compression. The three is to remove the oil pipe on the high pressure pump, try to use the hand oil pump to pump oil and observe the oil valve. If there is oil overflow, explain the oil valve malfunction. Under normal conditions, the governor can also be adjusted to the maximum oil supply position, and the plunger is pried with a screwdriver. It can be seen that there is no bubble in the oil, and the spray nozzle can be directly installed to view the atomization. Experienced Shifu touches the high pressure oil pipe during start-up. It pulsates but does not start. The reason is that the nozzle is not pulsating because of the high pressure pump.