The valve is screwed into the rear of the HPTC.
VN 9.039 1. Pressure regulating valve in the high pressure fuel system Y74
Valve design
VN 9.040 1. Fuel inlet year high pressure; 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 9.041
VN 9.041 Pressure control valve in the high pressure fuel system Y74. 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
Fuel supply control valve in the high-pressure fuel pump
The fuel supply control valve (Y94), together with the fuel injection pump pressure control valve (Y74), regulates the fuel pressure in the fuel injection pump (M41) and cuts off the fuel supply to the fuel injection pump plungers when the engine is stopped.
The fuel supply control valve to the high-pressure fuel pump is fixed to the high-pressure fuel pump flange.
VN 9.042 1. Fuel supply control valve Y94
VN 9.043 1. Fuel supply control valve Y94; a. Fuel supply; B. Adjustable fuel tray; c. Electrical connector
Valve operation
The fuel supplied by the fuel booster pump enters the fuel injection pump flange, passes through its channels through the fuel temperature sensor (1) to the fuel supply control valve (2) and to the fuel pressure relief valve (23).
The fuel supply control valve (2) varies the fuel flow in accordance with signals sent by the control unit CDHN3/9).
VN 9.044 1. Fuel temperature sensor B50; 2. Fuel supply control valve Y94; 3. High pressure channel; 4. Cam disc; 5. Eccentric shaft; 6. Fuel supply to the high-pressure circuit; 8. Valve spring; 9. Plungers; 10. Plunger springs; 15. Ball valve; 16. Return flow; 19. Valve; 20. Fuel injection pump flange; 21. Annular channel; 22. Fuel supply; 23. Fuel pressure relief valve; a. Zero feed throttle; b. Lubrication and ventilation hole; c. Lubricant supply
(Information copied from the website mercedesman)