RAM 1500 Truck 4WD V8-5.7L VIN D (2005)
Fuel Pressure Regulator: Description and Operation
A combination fuel filter and fuel pressure regulator (3) is used on all engines. It is located on the top of the fuel pump module. A separate frame
mounted fuel filter is not used with any engine.
Both fuel filters (at bottom of fuel pump module and within fuel pressure regulator) are designed for extended service. They do not require normal
scheduled maintenance. Filters should only be replaced if a diagnostic procedure indicates to do so.
Fuel Pressure Regulator Operation: The pressure regulator is a mechanical device that is not controlled by engine vacuum or the Powertrain Control
Module (PCM).
The regulator is calibrated to maintain fuel system operating pressure of approximately 58 ± 2 psi at the fuel injectors. It contains a diaphragm,
calibrated springs and a fuel return valve. The internal fuel filter is also part of the assembly.
Fuel is supplied to the filter/regulator by the electric fuel pump through an opening tube at the bottom of filter/regulator.
The regulator acts as a check valve to maintain some fuel pressure when the engine is not operating. This will help to start the engine. A second check
valve is located at the outlet end of the electric fuel pump. Refer to Fuel Pump Description and Operation for more information.
If fuel pressure at the pressure regulator exceeds approximately 60 psi, an internal diaphragm opens and excess fuel pressure is routed back into the tank
through the bottom of pressure regulator.
Both fuel filters (at bottom of fuel pump module and within fuel pressure regulator) are designed for extended service. They do not require normal
scheduled maintenance. Filters should only be replaced if a diagnostic procedure indicates to do so.