Fuel Pressure: Testing and Inspection

Fuel System Schematic:

WARNING: To reduce the risk of fire and personal injury, it is necessary to relieve the fuel system pressure before connecting a fuel pressure test. A small amount of fuel may spill when disconnecting fuel hoses. Always wrap a shop towel around fittings to catch any fuel that may leak out.

FUEL PRESSURE TEST CONNECTION

1. Connect fuel pressure gage J34730-1, or equivalent, to the fuel pump test connector located near the throttle body assembly. The test connector is a screw type quick connect fitting that resembles an air conditioning test fitting.
2. Apply battery voltage to the fuel pump test connector. See COMPONENT LOCATIONS.
3. Note fuel pressure.


FUEL RETURN RESTRICTION HOOKUP

NOTE: Proceed with this part only if directed by CHART A-7. This part of the procedure is used only to test for fuel line restrictions when the fuel pressure exceeds 13 psi (90 kPa).
1. Loosen fuel filler cap to relieve fuel tank vapor pressure
2. Disconnect negative battery cable to prevent fuel discharge if an accidental attempt is made to start the engine.
3. Locate engine compartment fuel return line quick-disconnect fitting.
4. Grasp both ends of fitting, twist female end 1/4 turn in each direction to loosen any dirt in the fittings.
5. Using compressed air, blow dirt out of quick disconnect fitting.
6. Using J37088-2, or equivalent, insert tool into female end of connector, then push inward to release male connector.
CAUTION: To reduce the risk of fire and personal injury: Before connecting the fuel line quick connect fitings, always apply a few drops of clean engine oil to the male tube ends. This will ensure proper reconnection and prevent a possible fuel leak. During normal operation, the fuel line O-rings will swell and may prevent proper reconnection if not lubricated.
7. Lubricate the male end of the fuel line and the fuel pressure test adapters with engine oil.
8. Connect the adapters to fuel return lines pushing the connectors together to cause the retaining tabs to snap into place. Once installed, pull on both ends of each connection to make sure it is secure.
9. Connect negative battery cable.
10. Check fuel pressure and proceed with tests as directed by CHART A-7.
11. Disconnect negative battery cable.
12. Disconnect fuel shut-off adapter from fuel return line.
13. Lubricate the male end of the fuel line and the fuel pressure test adapters with engine oil, and reconnect quick connect to make sure it is secure. Push connector together to cause the retaining tabs to snap into place. Once installed, pull on both ends of the connectors to make sure it is secure.
14. Tighten fuel filler cap.
15. Connect negative battery cable.
16. Cycle ignition ON and OFF twice, waiting ten seconds between cycles, then check for fuel leaks.
17. Install new O-rings as needed on fuel feed lines.
18. Reconnect fuel lines.
19. Connect negative battery cable.
20. Cycle ignition key ON to pressurize fuel system and check for leaks.

NOTE: For fuel system and component pressure test, refer to Computers and Control Systems. Testing and Inspection