Originally Posted by xfire2005

Hope this helps.

Description and Operation

The combination Fuel Filter/Fuel Pressure Regulator (4) consists of a housing with an integrated filter element. The fuel flows through the filter from the outside to the inside. As a result, any impurities are trapped inside the filter.

FUEL PRESSURE REGULATOR

The combination Fuel Filter/Fuel Pressure Regulator (2) is located along side of the fuel pump as part of the fuel filter assembly. It is transversely mounted to a chassis crossmember (left-to-right).

FUEL PRESSURE REGULATOR

Fuel Pressure Regulator
The Fuel Pressure Regulator is a mechanical device that is calibrated to maintain fuel system operating pressure of between 3.7 - 4.1 bar (54 - 60 psi ) at the fuel injectors.

Fuel is supplied to the Fuel Filter/Fuel Pressure Regulator by the Electric Fuel Pump directly.

The fuel pump assembly contains a check valve to maintain some fuel pressure in the system when the engine is not operating.

If fuel pressure at the pressure regulator exceeds a set amount, an internal diaphragm closes and excess fuel pressure is routed back into the tank through the pressure regulator.

The Diaphragm Pressure Regulator (2) regulates the fuel pressure by means of the return flow (10) quantity to the fuel tank.

If the pressure rises above the set pressure, the diaphragm (6) is pressed further against the compression spring (4).

The valve (7) attached to the diaphragm opens the passage for the return flow further. If the pressure drops below the set pressure, the valve is closed again by the compression spring (4).

FUEL FILTER
The fuel flows through the Fuel Filter (1) trapping any fuel impurities that may lie in the bottom of the tank. The Fuel Filter can not be serviced separately from the pressure regulator, the entire Fuel Filter/Fuel Pressure Regulator must be replaced as an assembly. For complete Fuel Filter/Fuel Pressure Regulator removal procedures.
Service and Repair

1. Remove the fuel filler cap from the fuel filler neck.
2. Remove the fuel pump fuse from the relay control module (3) located next to the PCM.
3. Start and run engine until it stalls.
4. Attempt restarting engine until it will no longer run.
5. Turn ignition key to OFF position.
6. Return the fuel pump fuse to the relay control module.
7. One or more Diagnostic Trouble Codes may have been stored in PCM memory due to fuel pump fuse removal. The DRB III(R) scan tool must be used to erase any DTCs.

Service and Repair
REMOVAL

1. Raise and support the vehicle.
2. Remove the fuel pump splash shield. WARNING: THE FUEL SYSTEM IS UNDER CONSTANT FUEL PRESSURE EVEN WITH THE ENGINE OFF. BEFORE DISCONNECTING ANY FUEL LINES, THIS PRESSURE MUST BE RELEASED.
3. Release the fuel system pressure. NOTE: Place a shop towel around fuel lines to catch any excess fuel during disassembly.
4. Remove the fuel filter/pressure regulator fuel line (1).
5. Remove the fuel rail supply line (3) at the fuel filter/ pressure regulator.
6. Remove the fuel delivery hose.
7. Remove the fuel return hose at the fuel filter/pressure regulator.
8. Remove the clamp retaining screw and remove the fuel filter/pressure regulator.

INSTALLATION

1. Position the fuel filter/pressure regulator into the clamp, install the retaining screw and tighten.
2. Install the following hoses/lines in order:

1. The fuel return hose.
2. The fuel delivery hose.
3. The fuel rail supply line (3).
4. The fuel filter/pressure regulator fuel line (1).

1. Tighten the hoses/lines to the fuel filter/pressure regulator.
2. Install the fuel pump splash shield.
3. Lower the vehicle.