Fuel Pump: Testing and Inspection

Fuel Tank And Related Components:

Fuel Pump Assembly:

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 Pump/Gauge Electrical Connector:

Fuel Tank Electrical Harness Connector:

If not, remove trunk floor covering and fuel tank access panel, disconnect electrical connector at the tank and repeat step 3 while monitoring voltage between terminals #1 and #4 of the harness connector.

^ 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).

PUMP AND CHECK VALVE CHECKING

NOTE: Before opening any fuel system connection, always relieve system pressure. To relieve fuel system pressure, disconnect fuel pump electrical connector at the pump, then start and run engine until it dies. Re-connect fuel pump connector. If engine does not run, slowly and carefully loosen a hose connection at the fuel filter. Cover with a clean rag while doing so to avoid spraying fuel in your face.

WARNING: FIRE HAZARD! Do not smoke or create any sparks where odor of fuel vapor is present.

PRESSURE CHECK - PREPARATION

Fuel Rail Connection To Pressure Regulator:

1. Disconnect fuel line to pressure regulator at fuel rail.

Removing Pressure Regulator:

2. Remove fuel pressure regulator from intake manifold and disconnect fuel lines.

Fuel Connection Installed Position For Testing:

3. Re-install line on fuel rail as shown in illustration.

Pressure Regulator Installed For Testing:

4. Re-connect fuel return line and vacuum hose to pressure regulator with regulator positioned as show in illustration.

Connecting Fuel Pressure Gauge:

5. Connect fuel pressure gauge with shut-off valve between fuel rail and pressure regulator as shown in illustration. Special connectors may be necessary to do this. Leave shut-off valve to the open position.

NOTE: Gauge must be able to measure up to 103 psi (7 bar).

TESTING

Fuel Pump Relay Socket Terminal ID:

1. Remove fuel pump relay and energize fuel pump for about 30 seconds by connecting jumper wire between relay panel terminals #48 and #52 to purge the air from the lines, then disconnect wire.
2. Close shut-off valve on pressure gauge.
3. Connect jumper wire again, energizing fuel pump just long enough for fuel pressure to rise up to 80 psi (5.5 bar).

If fuel pump pressure does not reach this value, replace pump.

If pressure excedes this value, very carefully open shut-off valve on pressure gauge ti bleed off excess.

4. Wait 10 minutes and observe pressure reading (residual pressure).

^ Maximum pressure drop after 10 minutes 7 psi (0.5 bar).

If pressure drop is greater than specified, replace fuel pump check valve.

FUEL PUMP VOLUME CHECK

Checking Fuel Pump Volume:

1. Disconnect fuel supply line to fuel rail and connect an extension hose approx. 30" (75 cm) long.
2. Place open end of extension hose into a suitable measuring container.
3. Energize fuel pump for 15 seconds.

Volume Vs. Operating Voltage:

4. Compare amount of fuel collected in container with the chart.

^ Actual quantity should be at least that shown in chart for the operating voltage (approx. 2 volts less than battery voltage).

If pump delivers less than the specified amount of fuel, check for restricted fuel filter or supply line (pinched or kinked). If no restrictions are found, replace pump.