Grand Cherokee 2WD V8-4.7L VIN N (2000)
Fuel Pressure Regulator: Description and Operation
FUEL FILTER/FUEL PRESSURE REGULATOR
Fig. 3 Fuel Filter/Fuel Pressure Regulator Location
The combination fuel filter/pressure regulator is located in front of the fuel tank and above the rear axle (Fig. 3). It is transversely mounted to a
chassis crossmember (left-to-right). Fuel Line Identification: The filter/regulator is equipped with 3 fuel line fittings (2 at one end and 1 at the
other end). The single fitting facing the left side of the vehicle is the supply line to the fuel rail (Fig. 3). The 2 fittings facing the right side of the
vehicle are connected to the fuel tank. Of these 2 fittings, the fitting towards the front is used for fuel return to the fuel tank. The fitting towards the
rear is a pressure line.
Fuel Pressure Regulator Operation: The pressure regnlator 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. 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 psi, an internal diaphragm closes. Excess fuel is then routed into a separate fuel
return line and returned to the fuel tank through the top of the fuel pump module.
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.
