Common rail system consists of four core components.

The four core components of a common rail diesel engine system are the fuel injector, high-pressure pump, high-pressure fuel rail, and electronic control unit (ECU).

**Fuel Injector:** The common rail injector precisely injects fuel according to the timing and quantity calculated by the ECU.

**High-Pressure Pump:** The high-pressure pump compresses the fuel to a high-pressure state to meet the requirements for fuel injection pressure and quantity.

**High-Pressure Fuel Rail:** The high-pressure fuel rail suppresses pressure fluctuations in the fuel supply from the high-pressure pump and the fuel injection from the injectors through energy storage.

**ECU:** The ECU acts like the brain of the engine, controlling engine operation and diagnosing faults.

● Two Distinctive Features: High-Pressure Fuel Rail and ECU

The most obvious visual difference between a common rail system and a conventional diesel engine fuel system is the presence of two distinct features: the high-pressure fuel rail and the ECU.