How to troubleshoot the diesel engine common rail pipe?

The task of the common rail pipe of the diesel engine is to store high-pressure fuel, and the pressure fluctuations generated by the fuel supply and fuel injection of the high-pressure pump are buffered by the volume of the common rail pipe. When outputting a large amount of fuel, the common rail pressure shared by all cylinders should also be kept constant, so as to ensure that the fuel injection pressure remains unchanged when the injector is opened.

The task of the common rail pipe is to store high-pressure fuel, and the pressure fluctuations generated by the fuel supply and fuel injection of the high-pressure pump are buffered by the volume of the common rail pipe. When outputting a large amount of fuel, the common rail pressure shared by all cylinders should also be kept constant, so as to ensure that the fuel injection pressure remains unchanged when the injector is opened.

 

The common rail is installed with a common rail pressure sensor, a common rail pressure limiting valve, and a flow limiter. Due to the different installation conditions of the diesel engine, the common rail pipe with flow limiter (option), common rail pressure sensor, pressure regulating valve and pressure limiting valve can be designed differently. The common rail pipe is usually filled with high-pressure fuel, making full use of the high pressure to compress the fuel to maintain the storage pressure, and using a high-pressure pump to compensate for the pressure fluctuations caused by the pulsating fuel supply, so even if the fuel is injected from the common rail pipe, the common rail The pressure in the tube is also approximately constant. The failure of the rail pressure sensor and the pressure limiting valve can easily cause difficulty in starting.

 

Common rail tube common failure causes and troubleshooting methods are as follows:

 

Fault type 1: Analysis of the cause of abnormal leakage of the pressure limiting valve: The pressure limiting valve is not tightly sealed or the pressure limiting valve spring fails, causing the rail pressure to be less than 160.0MPa, and the fuel will be expelled from the pressure relief valve. Treatment method: replace the pressure limiting valve or common rail pipe (Note: the rail pressure cannot be established normally)

 

Fault type 2: Analysis of the fault of the rail pressure sensor: poor contact of the plug and damage to the rail pressure sensor. Treatment method: re-pull the plug or replace the rail pressure sensor. (Note: The rail pressure is unstable and irregular; the signal voltage of the rail pressure sensor is about 1V when idling.