RAM 3500 Van V8-5.9L VIN Z LDC (1998)
Fuel Pressure Regulator: Description and Operation
Fig 3 Side View -- Filter/Pressure Regulator
DESCRIPTION
A combination fuel filter and fuel pressure regulator 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.
OPERATION
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 339 kPa ± 34 kPa (49.2 psi ± 5 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. If fuel pressure at the pressure regulator exceeds approximately 49.2 psi, an internal diaphragm opens and
excess fuel pressure is routed back into the tank through the bottom of pressure regulator.
