Supercharger failure: Insufficient air intake of the excavator may be caused by valve failure in individual cases. When the excavator maintenance fuel supply is too large, it is the same as "insufficient air intake". When the fuel supply is too large, the normal amount of air entering the cylinder cannot satisfy the complete combustion of the excess diesel, which will cause the carbonization of the diesel, which will be exhausted along with the exhaust. When the air is exhausted, it is black smoke. The reason for the excessive oil supply of the excavator is often human intervention: for example, the cylinder pressure caused by adjusting the oil pump is not enough; the cylinder pressure mentioned here refers to the maximum pressure generated by the engine in the cylinder during the compression stroke, when the piston ring leaks. Insufficient cylinder pressure will be caused when the gas and gas valves are not tightly closed and the intake air is insufficient. At this time, due to insufficient pressure and temperature, the diesel fuel injected into the combustion chamber cannot burn well and even cannot burn to do work, so it becomes carbon deposits and is discharged. For excavators that have been used for a long time, this situation is more common. Especially when the lower exhaust is serious, the above phenomenon often occurs, which indicates that the engine needs to be overhauled.

Ignition timing (fuel supply advance angle) is incorrect: Each type of excavator engine has a fixed fuel supply advance angle. This fuel supply advance angle is a very important condition to ensure the normal operation of the engine. The cylinder pressure, temperature and other conditions corresponding to the fuel supply at this advance angle are very beneficial to the combustion of diesel, otherwise the excavator will be discharged due to poor combustion. cigarette. This kind of failure often occurs after the disassembly of the diesel pump; sometimes it is also caused by the unexpected change of the relative position between the diesel pump shaft of the excavator and the timing gear.

Poor atomization: When the piston runs to a certain position at the top dead center, diesel fuel is sprayed into the combustion chamber in a mist form to burn and do work, and the quality of atomization directly affects the quality of combustion. When the quality of diesel oil cannot be guaranteed, it is very easy to cause damage or jam of the fuel injection head, resulting in poor atomization or even no atomization. At this time, it is often accompanied by damage to the plunger of the diesel pump and insufficient power of the excavator.