Fuel Pump: Testing and Inspection

This is the same testing procedure as the one found under FUEL SYSTEM PRESSURE TEST.

NOTE: This testing procedure will test the following to avoid misdiagnosis of an individual component:
a. Fuel pumps
b. Pressure regulator
c. Fuel lines
d. Fuel system pressure

Connecting Fuel Pressure Tester:

1. Turn ignition OFF.
2. Connect pressure gauge (Volvo tool #5011 or equivalent) as shown in the image. Use Volvo hose #5116, adapter set #5332 and nipple #5265 or equivalent to install tester.

WARNING: Fuel lines are under pressure. When disconnecting fuel lines, cover the connection with a shop towel to protect yourself from the excess pressurized fuel.

3. Open the valve of pressure gauge to center position.

Bridging System Relay:

4. To start fuel pumps, remove the [1][2]system relay (located in center console behind ash tray).
5. Connect a lead between terminals 30 and 87/2 on relay base. The fuel pumps should start operating. Check by listening to the pumps. Fuel tank pump can be heard by removing the tank cap.
a. If fuel pumps run, proceed with step 10.
b. If fuel pump(s) do not run, proceed with next steps.
6. Remove the wire between terminals 30 and 87/2.
7. Check that terminal 30 has system voltage. If not, repair wire or connection between relay socket and battery.
8. Reconnect the wire between terminals 30 and 87/2.
9. Fuel pumps should now operate. If not:
a. Check wire between relay socket and fuel pumps. Repair as needed.
b. Check fuel pump ground wires. Repair as needed.
c. Check wire between terminals 85 and 87/1 with an ohmmeter. Repair as needed.
If all wiring (as tested above) is in good working order, replace and retest with new fuel pump(s).

Opening The Valve:

10. With fuel pumps running, measure system pressure.

Reading: 250 kPa (36 psi)

If reading is correct, proceed with step 11.
If reading is incorrect, proceed with the next steps.

Fuel System Pressure To High:

a. Pressure to high:
Remove electrical lead between terminals 30 and 87/2.
Remove fuel return pipe from pressure regulator and blow through it. Repair or replace if restricted and retest.
Remove vacuum hose from pressure regulator and blow through it. Repair or replace if restricted and retest.
If both lines are free of restriction and fuel pressure remains to high, replace and retest with new fuel pressure regulator.

Fuel System Pressure To Low:

b. Pressure to low:
Pinch fuel return line with hand and check pressure increase.

CAUTION: Do not allow the pressure to exceed 600 kPa (87 psi).

If pressure rises quickly, pumps and fuel lines are O.K.. Replace fuel regulator and retest.
If fuel pressure rises slowly, this indicates a blocked fuel filter, tank pump or supply line. Check the individual components and replace as needed.
If pressure does not rise, main fuel pump is defective. Replace and retest with new pump.

Checking Pressure Regulator:

11. Check the fuel pressure regulator by disconnecting the vacuum hose and connecting a vacuum pump to the pressure regulator.
12. While monitoring the pressure gauge, apply vacuum to the pressure regulator. Check that the fuel system pressure drops as vacuum increases. Diaphragm must be able to retain the vacuum applied, no bleed-off should occur.
If pressure regulator does not perform correctly, replace and retest with new pressure regulator.
13. Disconnect the vacuum pump.
14. Disconnect fuel pump relay lead.
15. Disconnect all test equipment and reconnect all hoses and the relay. Use new washers on the fuel line connectors.

WARNING: Fuel lines are under pressure. When disconnecting fuel lines, cover the connection with a shop towel to protect yourself from the excess pressurized fuel.

16. Run engine and recheck fuel line connections for leakage.