The diesel engine is difficult to start,flameout after starting, the exhaust pipe does not smoke, and white smoke or only small black smoke emerges.

First of all, check whether there is air in the oil circuit, and observe whether the oil circuit is not tightly sealed or there is gas leakage.The most common leakage parts are pipe joints, gaskets, oil inlet valve, oil outlet valve. When checking, pull the throttle control handle to the maximum oil supply position and pump oil with the hand pump. At the same time, loosen the gas release plug on the fuel fine filter or the oil pump body, and there are bubbles and oil droplets discharged from the mouth of the gas release pipe, indicating that there is air in the oil circuit. At this time, while pumping oil with a hand pump (can also be carried out in the case of the car), unscrew the air plug and discharge continuously until the fuel flows smoothly without bubbles. If the air is not discharged, it indicates that there is still air intake in the oil circuit, which must be checked and excluded step by step.

After removing the air from the oil circuit, check the low-pressure oil circuit. For models with piston type oil pumps, it is advisable to use the oil pump as the dividing line for inspection. When lifting the handle of the hand-operated oil pump upwards, there is a feeling of difficulty and suction, but when pressing the handle, it is easy and there is no pump resistance, indicating that there is a blockage in the front of the hand-operated oil pump (including the coarse filter, fuel tank pipeline, switch). Because when the oil circuit before the oil pump is blocked, lifting the hand pump creates a vacuum in the lower chamber of the piston, which generates suction on the piston, making it difficult to lift the hand pump. On the contrary, if there is significant and heavy resistance when using a manual fuel pump to pump oil, it indicates that the oil circuit after the fuel pump is blocked (such as a clogged fuel fine filter). The lack of oil supply or insufficient oil supply of the fuel pump is generally caused by the poor sealing of the inlet and outlet valves and seats of the fuel pump, piston wear, piston spring failure, and other reasons. To check the tightness of the fuel inlet valve, the oil pump can be removed and the inlet valve spring can be compressed by 0.5-1mm with your fingers to prevent fuel from rushing out. If the inlet valve is not tightly sealed, the oil level will slowly rise. To determine the sealing performance of the piston and oil outlet valve, the manual oil pump can be installed to restore its original state. Use the manual oil pump to pump oil several times, then gently press down on the handle and observe the lifting of the handle.

If the handle remains stationary in its original position, it indicates that the oil outlet valve has good sealing performance; If the handle rises slowly, it indicates poor sealing of the oil outlet valve; If the handle rises quickly, it indicates that the oil outlet valve cannot be closed or the piston is severely worn (during this inspection, the hand pump and inlet valve of the oil pump should have good sealing). After the fault of the low pressure oil circuit not supplying oil has been checked and eliminated, if the oil is still not supplied, the high pressure oil circuit can be checked again. The method is to loosen the high-pressure oil pipe joints of each cylinder, place the throttle control handle in the maximum fuel supply position, and shake the car to observe the oil discharge of each high-pressure oil pipe joint. Normally, during fuel supply, the fuel can surge high, otherwise it means that the high-pressure oil circuit is not receiving fuel. The fuel pump should be removed to check the window cover. Whether the rack is flexible and in the maximum fuel supply position, otherwise it indicates that the rack is stuck or the throttle lever adjustment is inappropriate; Whether the plunger arm and plunger are slipping and malfunctioning, and whether the plunger spring is broken.