Fuel Pump: Testing and Inspection

Fig. 24 Fuel Pump Bypass Terminal I.D.:

1. Ensure that fuel filter is clean and correctly installed and that No. 5 fuse and/or fuel pump relay is not defective.
3. Disconnect electrical connectors from fuel pressure regulator and auxiliary air valve.
4. Remove fuel pump relay from the fuse/relay panel and connect jumper wire with an in-line switch (US4480/3 or equivalent), Fig. 24, ensuring that switch is in OFF position.

Fig. 63 Fuel Pump Assembly:

5. Connect voltmeter to fuel pump (located in the top of the fuel tank, Fig. 63), then turn on jumper wire switch and check voltage. Battery voltage should be available.
6. Disconnect flexible fuel return line that runs from fuel distributor to the metal fuel tank line, at the metal line connection, and insert the end of the flexible line in a calibrated container.
Do not open fuel tank cap until after fuel delivery rate has been checked.
7. Turn jumper wire switch on for 30 seconds.
8. Fuel delivery rate should be:
760 ml @ 12 volts
600 ml @ 11 volts
460 ml @ 10 volts
330 ml @ 9 volts
9. If fuel delivery is not within specification, check:
a. Fuel return line for blockage,
b. Faulty fuel pressure regulator in fuel distributor,
c. Clogged fuel filter
d. Blocked fuel pressure line,
e. Clogged fuel pump pickup screen.

Fig. 62 Fuel Supply Component Layout:

10. If the fuel flow path is OK, check the voltage supply and current draw of the fuel pump, Fig. 62.
11. To gain access to the fuel pump fittings, remove fuel accumulator, leaving fuel lines connected.
12. Disconnect electrical connectors at fuel pump (located at the top of the fuel tank, as part of the fuel level sender).
13. Connect voltmeter to fuel pump, then turn on jumper wire switch and check voltage. Battery voltage should be available. Do not let positive connection contact ground. If battery voltage is not available, check all terminal connections, fuses and wiring.
14. Turn off jumper wire switch and connect ground lead to fuel pump.
15. Connect ammeter between positive lead and fuel pump and turn on jumper wire switch. If, with proper voltage, amperage exceeds 8.5 amps, replace fuel pump.
16. Turn off jumper wire switch, remove ammeter and attach electrical connector to fuel pump.