Ok! I misunderstood fuel pressure controller, you mean the fuel pressure regulating valve!
The fuel pressure is adjusted to between 50 and 100 bar by the fuel pressure regulating valve (N276)
Task
The task of the fuel pressure regulating valve is to adjust the fuel pressure in the fuel rail irrespective of the injection quantity and pump
delivery rate.
This is how it works
If deviations from the setpoint pressure are detected, the fuel pressure regulating valve is activated by a pulse-width modulated signal
from the engine control unit. As a result of this, a magnetic field is induced in the magnetic coil and the valve with the valve ball lifts off the valve
seat. In this way, the flow cross-section to the return line is changed depending on signal size, thus altering the discharge rate and regulating
the fuel pressure.
Failure strategies
The regulating valve is closed in de-energized state. This ensures that sufficient fuel pressure is always present. To protect the components
against excessively high pressures, a spring operated mechanical pressure limiting device is built into the fuel pressure regulating valve. It
opens at a fuel pressure of 120 bar.