Fuel Pressure: Testing and Inspection
FUEL SYSTEM PRESSURE TEST AND INJECTOR BALANCE TESTTOOLS REQUIRED
J 34730-1A Fuel Pressure Gage
J 39802 Fuel Pressure Gage Adapter
J 34730-3A Fuel Injector Tester
J 34730-355 Fuel Injector Test Harness Adapter
PURPOSE
A fuel system pressure test and fuel injector balance test determines if the Multiport Fuel Injection (MFI) system is functioning correctly from a fluid (gasoline) and electrical/mechanical (fuel injectors) perspective. To perform these tests, follow the procedure below:
PROCEDURE
1. Relieve fuel system pressure. Refer to Fuel Pressure Relief Procedure. Service and Repair
2. Remove one bolt and fuel feed hose bracket from bottom of intake manifold.
3. Remove one bolt and fuel feed hose from fuel rail.
4. Install J 39802 with gaskets and fuel feed hose to fuel rail. Tighten J 39802 bolt to 29 Nm (22 lb. ft.).
5. Connect J 34730-1A to J 39802.
6. Reconnect negative (-) battery cable. Tighten negative (-) battery cable-to-negative (-) battery cable terminal retainer to 15 Nm (11 lb. ft.).
7. Turn the ignition switch to "ON" and connect a jumper between the underhood Data Link Connector (DLC) terminals "+B" and "FP."
Measure
Fuel Pressure should be 265-304 kPa (38-44 psi).
Interpreting Results
If pressure is higher than the specifications, check for a plugged fuel return pipe/hose. If pipe/hose are OK, replace the fuel pressure regulator.
If pressure is lower than the specifications, check for leaks at hose-to-pipe connections, a leaking fuel pump or fuel pressure regulator. Repair/replace as necessary.
8. Remove the jumper from the Data Link Connector (DLC) terminals.
9. Start engine and remove and plug the vacuum hose from the fuel pressure regulator.
Measure
Fuel pressure. Should be 265-304 kPa (38-44 psi) at idle. Reconnect the vacuum hose to the pressure regulator and note fuel pressure at idle. Should drop to 206-255 kPa (31-37 psi).
Interpreting Results
If pressure is not within specifications for the above mentioned tests, repair/replace the vacuum hose or fuel pressure regulator as necessary.
10. Shut engine off.
Measure
Fuel pressure. Should remain above 147 kPa (21 psi) for at least five minutes after the engine was stopped.
Interpreting Results
If pressure is below the specification, check for a leaking fuel pump, pressure regulator and/or fuel injectors.
11. Disconnect the four fuel injector electrical connectors.
12. Turn the ignition switch to "ON" and momentarily connect a jumper between DLC terminals "+B" and "FP."
13. Install one end of J 34730-355 to a fuel injector's terminals and the other end to J 34730-3A.
14. Connect J 34730-3A to the battery.
15. Set J 34730-3A switch to one pulse and activate one time only.
Measure
Fuel pressure while activating tester. Should drop to 179-234 kPa (26-34 psi) after tester is activated.
Interpreting Results
If pressure is not within specifications, replace faulty fuel injector(s).
16. Repeat Steps 12 through 15 on the remaining fuel injectors.
17. Turn ignition switch to "LOCK" and reconnect all fuel injector electrical connectors.
18. Relieve fuel system pressure. Refer to Fuel Pressure Relief Procedure.
19. Remove one bolt and J 39802 and J 34730-1A from fuel rail.
20. Using two new gaskets, reconnect fuel feed hose to fuel rail; secure with one bolt. Tighten Fuel feed hose bolt to 29 Nm (22 lb. ft.).
21. Reconnect fuel feed hose bracket to intake manifold; secure with one bolt. Tighten fuel feed hose bracket bolt to 10 Nm (89 lb. in.).
22. Reconnect negative (-) battery cable. Tighten negative (-) battery cable-to-negative (-) battery cable terminal retainer to 15 Nm (11 lb. ft.).
23. Turn ignition switch to "ON" and momentarily connect a jumper between DLC terminals "+B" and "FP." Check for any fuel leaks.