Fuel Pump: Testing and Inspection

Fuel Tank Assembly:

Fuel Pump Operation:

FUEL PUMP ELECTRICAL CHECK

1. Turn ignition "ON" and listen for fuel pump.

^ Fuel pump should run for approx. 5 seconds when ignition is turned "ON" (should be audible but you may need a second person listening at the fuel filler with the filler cap removed, to tell if it's operating).

If OK, go to FUEL PUMP PRESSURE AND CHECK VALVE TEST (below).

If not OK, check fuel pump relay and fuse #13 (see FUEL PUMP RELAY in this section).

Fuel Pump Relay Socket Terminal ID:

2. Remove fuel pump relay and connect jumper wire between relay panel terminals #48 and #52.

^ Fuel pump should run (should be audible, but you may need a second person listening at the fuel filler with the filler cap removed, to tell if it's operating).

Fuel Tank Electrical Harness Connector:

If not, disconnect electrical connector at the tank and repeat step 3 while monitoring voltage between terminals #1 and #4 of the harness connector at the tank.

^ Should have battery voltage while jumper wire is connected. If voltage is OK and pump does not run, replace pump. If no voltage is present, check for open or short to ground in wiring between fuel pump relay terminal #52 and fuse #13, or between fuse #13 and fuel pump (see CHASSIS ELECTRICAL DIAGRAMS).

FUEL PUMP PRESSURE AND CHECK VALVE TEST

Fuel Supply Line Connection To Fuel Rail:

Connecting Pressure Gauge:

1. Connect fuel pressure gauge between fuel supply line and fuel rail using adapters, as shown in illustration.
2. Set valve on pressure gauge block to the closed position.
2. Operate fuel pump until gauge pressure is approx. 80 psi (5.5 bar), then turn pump "OFF", noting pressure. (Operate pump by bridging terminals of fuel pump relay socket as in step 2 of electrical test above.)
3. Wait 10 minutes and note pressure drop.

^ Pressure drop should not excede 7.4 psi (0.5 bar).

If pressure drop is greater than specified, check hoses and connections for leaks. If no leaks are found, replace fuel pump check valve.

FUEL PUMP VOLUME TEST

Checking Fuel Pump Volume:

1. Disconnect fuel hose from gauge and push a long piece of hose over the supply line from the pump, directing open end of extra hose into a suitable measuring container (see illustration).
2. Remove fuel filler cap.
3. Connect voltmeter between electrical terminals of fuel pump, with pump connected.
4. Energize fuel pump for 15 seconds (see step 2 of electrical test above) and note operating voltage at the pump.

Fuel Pump Volume Vs. Supply Voltage:

5. Check volume of fuel in container after 15 seconds of operation and compare with chart.

^ If volume is less than that specified for the noted operating voltage, check for restricted or plugged fuel filter and/or supply line. If filter and line are OK, replace fuel pump.