Purpose
The pressure regulating valve in the high-pressure fuel pump (Y74) maintains the pressure at a level set by the engine control unit (A53).
Accommodation
The pressure control valve in the HPC is attached using a thread in the rear end of the HPC (see figure VN 2.119 pos. 6 and 2),
Design
VN 2.126
1. High pressure fuel inlet
2. Fuel drain holes in the return line
3. Pressure regulating valve in the high pressure fuel pump (Y74)
Functioning
The principle of operation is shown in the figure VN 2.127.
VN 2.127
Pressure regulating valve in the high pressure fuel system
Operating principle
1. Fuel inlet
2. Solenoid
a. The force developed by the solenoid
B. The force developed by the spring
c. Ball valve seat