Fuel Pump: Service and Repair

Electric Fuel Tank Pump And Sender Assembly - 7.5L Engine - Typical:

NOTE: Each time the electric fuel pump is removed from the fuel tank, the rubber hoses and clamps Must be replaced (in addition to the mounting gasket). When the rubber hoses become exposed to the air outside the tank, the air reacts with the fuel soaked rubber, eventually causing the hoses to become brittle, even if the hoses are returned to the tank. This deterioration seriously weakens the hoses and will lead to premature failure of the hoses.

CAUTION: Fuel supply lines will remain pressurized for long periods of time after engine shut down. This pressure must be relieved before servicing of the fuel system is begun. A valve is provided on the fuel charging assembly for this purpose. Remove the air cleaner. Attach Tool T8OL-9974-A or equivalent to the fuel diagnostic valve on the fuel charging assembly Pressure in the fuel system may now be released.

Removal

1. Place vehicle on hoist, do not raise.
2. Depressurize fuel system as previously described.
3. Remove fuel from fuel tank by pumping out through filler. Use care to prevent combustion from fuel spillage.
4. Raise vehicle on hoist.
5. Disconnect supply line and return line fittings and vent line at the right and left hand side rear axle frame kick-ups.
6. Disconnect electrical connector forward of tank.
7. Disconnect and remove fuel filler tube.
8. Remove fuel tank support straps and remove fuel tank to bench.
9. Remove any dirt that has accumulated around the fuel pump attaching flange so that it will not enter the tank during removal and installation.
10. Disconnect the supply line and return line fittings and the electrical connector.
11. Turn the fuel pump locking ring counterclockwise with the tool and remove locking ring.
12. Remove fuel pump and bracket assembly.
13. Remove seat gasket and discard.


Installation

1. Clean the fuel pump mounting flange and the fuel tank mounting surface and seal ring groove.
2. Put a light coating of heavy grease (C1AZ-19590-B or equivalent) on a new seal ring to hold it in place during assembly and install in fuel ring groove.
3. Install fuel pump and bracket assembly carefully to insure that filter is not damaged. Be sure that locating keys are in keyways and seal ring remains in groove.
4. Hold pump assembly in place and install locking ring fingertight being sure that all locking tabs are under tank lock ring tabs.
5. Secure the fuel pump unit with the locking ring by rotating clockwise with tool until ring stops against stops.
6. Install electrical connector.
7. Lubricate fittings and install fuel line fittings and tighten to 13-20 Nm (10-15 lb ft).
8. Install tank in vehicle, and tighten straps.
9. Connect electrical connections to fuel sender and fuel pump wiring harness.
10. Lower vehicle.
11. Install filler tube and attaching screws.
12. Connect vent line.
13. Lube fittings on right and left side of vehicle at kickup with light oil. Install fitting fingertight, then tighten 1/4 turn more.
14. Install a minimum of 38 liters (10 gallons) of fuel and check for leaks.
15. Install pressure gauge Tool T8OL-9974-A or equivalent on the fuel charging assembly fuel diagnostic valve. Turn ignition key to On position for 3 seconds. Turn ignition key Off and back On for 3 seconds repeatedly (5 to 10 times) until pressure gauge shows at least 241 kPa (35 psi). Check for leaks at fittings.
10. Remove pressure gauge, start engine, and recheck for leaks.