Fuel Pressure Regulator: Testing and Inspection

NOTE: To relieve fuel system pressure, remove trunk floor cover and fuel pump access cover, disconnect fuel pump electrical connector at the pump, then start and run engine until it dies. Re-connect fuel pump connector.

Connecting Pressure Gauge:

1. Relieve fuel system pressure and connect fuel pressure gauge between fuel supply line and fuel rail using adapters, as shown in illustration.

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

2. Set valve on pressure gauge block to the open position.
3. Disconnect and plug vacuum hose to pressure regulator.

Fuel Pump Relay Socket Terminal ID:

4. Remove fuel pump relay and connect jumper wire between relay panel terminals #48 and #52 (turns fuel pump "ON").
5. Observe pressure reading on gauge (This is the system operating pressure).

^ System pressure should be 58 - 62 psi (4.0 - 4.3 bar)

If system pressure is too low, check for:
^ Restricted fuel filter.
^ Pinched, kinked or leaking fuel supply line.
^ Faulty fuel pressure relief valve in fuel pump or defective pump (See FUEL PUMP in this section).

If these check out OK and pressure is still too low, replace pressure regulator.

If system pressure is too high, check for restricted fuel return line. If return line is OK, replace pressure regulator.

6. Re-connect vacuum hose to pressure regulator and start engine.
^ System pressure should be 50 - 54 psi (3.4 - 3.7 bar).

If not, check vacuum hose routing (should have manifold vacuum of 17" - 20" Hg at pressure regulator vacuum hose with engine idling). If vacuum is OK and pressure does not drop when hose is connected, replace pressure regulator.

7. Turn engine "OFF" and remove jumper wire from fuse relay panel.

8. Wait about 10 minutes and check residual pressure.

^ Should be 43 psi (3.0 bar) minimum.

If residual pressure is less than specified, check for:
^ Leaking fuel injectors.
^ Faulty check valve in fuel pump (see FUEL PUMP in this section).
^ Leaking fuel supply line or connections.

If these are OK, replace pressure regulator.

NOTE: There should not be any fuel present at the vacuum connection of the regulator. If there is, replace it.