Bosch-Common Rail System – Fuel rail (common rail)

1 Fuel pressure sensor

The fuel rail is made of forged steel.

The common rail performs the following functions:

• stores fuel under high pressure and
• minimizes pressure fluctuations.

Pressure fluctuations are induced in the high-pressure fuel system due to the operating movements in the high-pressure chambers of the high-pressure pump and the opening and closing of the solenoid valves on the fuel injectors.

Consequently, the fuel rail is designed in such a way that, on the one hand, it possesses sufficient volume to minimize pressure fluctuations, but, on the other hand, the volume in the fuel rail is sufficiently low to build up the fuel pressure required for a quick start in the shortest time possible.


The fuel supplied by the high pressure pump passes through a high pressure line to the high pressure accumulator. The fuel is then delivered to the individual fuel injectors via the four injector tubes which are all of the same length.

When fuel is taken from the fuel rail for an injection process, the pressure in the fuel rail remains almost constant.

Fuel pressure sensor

In order that the engine management system can determine the injected fuel quantity precisely, as a function of current fuel pressure in the fuel rail, a fuel pressure sensor is provided on the fuel rail.

27. August 2018 by Ron
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