Removal & Installation
Fuel injection systems remain under pressure, even after the engine has been turned OFF. The fuel system pressure must be relieved before disconnecting any fuel lines. Failure to do so may result in fire and/or personal injury.
- If equipped with air suspension, the air suspension switch, located on a side panel of the trunk compartment, must be turned to the OFF position before raising the vehicle.
- Disconnect the negative battery cable.
- Relieve fuel system pressure using the recommended procedure.
- Raise and safely support the vehicle.
- Remove the fuel tank from the vehicle and place on a suitable work bench.
- Remove any dirt that has accumulated around the fuel pump retaining flange so it will not enter the tank during pump removal and installation.
- On 1988-94 models, turn the fuel pump locking ring counterclockwise and remove the locking ring.
- On 1995-00 models, remove the retaining bolts around the perimeter of the fuel pump module.
- Remove the fuel pump/sending unit assembly. Remove and discard the seal ring.
- Clean the fuel pump mounting flange, fuel tank mounting surface and seal ring groove.
- Apply a light coating of grease on a new seal ring to hold it in place during assembly and install it in the seal ring groove.
- Install the fuel pump/sending unit assembly carefully to ensure the filter is not damaged. Make sure the locating keys are in the keyways and the seal ring remains in the groove.
- Hold the pump assembly in place and install the locking ring finger-tight. Make sure all the locking tabs are under the tank lock ring tabs.
- Rotate the locking ring clockwise until the ring is against the stops.
- Install the fuel tank into the vehicle.
- Lower the vehicle.
- If equipped with air suspension, turn the air suspension switch to the ON position.
- Add a minimum of 10 gallons of fuel to the tank and check for leaks.
- Reconnect the negative battery cable.
- Turn the ignition switch to the RUN position several times to pressurize the fuel system. Check for fuel leaks and correct as necessary.
- Start the engine and check for leaks.
- Road test the vehicle and check for proper operation.
Observe all applicable safety precautions when working around fuel. Whenever servicing the fuel system, always work in a well ventilated area. Do not allow fuel spray or vapors to come in contact with a spark or open flame. Keep a dry chemical fire extinguisher near the work area. Always keep fuel in a container specifically designed for fuel storage; also, always properly seal fuel containers to avoid the possibility of fire or explosion.
- Check all hoses and lines for kinks and leaking. Repair as necessary.
- Check all electrical connections for looseness and corrosion. Repair as necessary.
- Turn the ignition key from the OFF position to the RUN position several times (do not start the engine) and verify that the pump runs briefly each time, (you will here a low humming sound from the fuel tank).
Check that the inertia switch is reset before diagnosing power supply problems to the fuel pump.
The use of a scan tool is required to perform these tests.
- Turn the ignition key OFF .
- Connect a suitable fuel pressure gauge to the fuel test port (Schrader valve) on the fuel rail.
- Connect the scan tool and turn the ignition key ON but do not start the engine.
- Following the scan tool manufacturer's instructions, enter the output test mode and run the fuel pump to obtain the maximum fuel pressure.
- The fuel pressure should be between 30-45 psi (210-310 kPa).
- If the fuel pressure is within specification the pump is working properly. If not, continue with the test.
- Check the pump ground connection and service as necessary.
- Turn the ignition key ON .
- Using the scan tool, enter output test mode and turn on the fuel pump circuit.
- Using a Digital Volt Ohmmeter (DVOM), check for voltage (approximately 10.5 volts) at the fuel pump electrical connector.
- If the pump is getting a good voltage supply, the ground connection is good and the fuel pressure is not within specification, then replace the pump.