Fuel System Pressure Test

FUEL SYSTEM PRESSURE TEST

Tools Required:
J34730-1A Fuel Pressure Gage
J39802 Fuel Pressure Gage Adapter

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 this test, follow the procedure below:

1. Relieve fuel system pressure. Refer to "Fuel System Pressure Relief Procedure" in this section.

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 J39802 with gaskets and fuel feed hose to fuel rail.

Tighten

^ J39802 bolt to 29 Nm (22 lb-ft).

5. Connect J34730-1A to J39802.

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 data link connector (DLC) terminals "+B" and "Fp.

Measure

^ Fuel Pressure. Should be 265-304 kPa (38-44 psi). 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 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). 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. If pressure is below the specification, check for a leaking fuel pump, pressure regulator and/or fuel injectors.