What is the solution for low common rail pressure?
2 Answers
For low common rail pressure, you can check if there is air in the fuel inlet pipe and then purge the air from the common rail. This is not a particularly complex solution. Related information: 1. Introduction: The common rail system mainly consists of an electronic control unit (ECU), high-pressure fuel pump, accumulator (common rail pipe), electronically controlled fuel injector, and various sensors. The low-pressure fuel pump delivers fuel to the high-pressure fuel pump, which then pressurizes the fuel and sends it to the high-pressure fuel rail (accumulator). 2. Expansion: The pressure in the high-pressure fuel rail is regulated by the electronic control unit based on the rail pressure measured by the rail pressure sensor and the required adjustments.
Last time my car showed a low common rail pressure warning, the mechanic taught me to first check the low-pressure fuel circuit. The focus was on whether the diesel filter was clogged, if there was enough fuel in the tank, and if there was any air leakage in the fuel lines. If the low-pressure circuit was fine, then the high-pressure fuel pump needed to be checked to see if the fuel inlet pressure was sufficient and if the metering valve was working properly. Some vehicles also require checking the fuel injector return flow—if one injector is leaking too much, the entire system pressure won’t rise. Sensors also need to be inspected; if the pressure sensor or rail pressure regulator valve malfunctions, the data won’t be accurate. Only then should internal wear in the high-pressure fuel pump be considered. Following this set of checks usually helps pinpoint the root cause—the key is to eliminate possibilities step by step.
