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N55 Engine
High Pressure Fuel Pump
The fuel is pressurized in the permanently driven three-piston high pressure pump and
delivered to the fuel rail via the high pressure line. The fuel stored under pressure in the
fuel rail is distributed via the high pressure lines to the high pressure fuel injection valves.
The required fuel pressure is determined by the engine management as a function of the
engine load and engine speed. The pressure level is registered by the rail pressure
sensor and sent to the engine control unit. The fuel is regulated by the quantity control
valve based on a target/actual value comparison of the rail pressure. The pressure level is
configured such to achieve the smoothest running properties with the best possible fuel
consumption. A pressure of 200 bar is only required at high load and low engine speed.
The high pressure pump is of the same design as the high pressure pump used on the
N54 engine.
N55, fuel pressure diagram
Index Explanation
m
Engine Load
n
Engine Speed
p
Pressure
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