Fuel Pump: Testing and Inspection

Fuel Pressure Test And Pressure Relief Hookup.:

WARNING: DO NOT ALLOW SMOKING OR THE USE OF OPEN FLAMES IN THE AREA WHERE WORK ON THE FUEL SYSTEM IS TAKING PLACE. ANYTIME THE FUEL SYSTEM IS BEING WORKED ON, DISCONNECT THE NEGATIVE BATTERY CABLE, EXCEPT FOR THOSE TESTS WHERE BATTERY VOLTAGE IS REQUIRED.

WARNING: WHENEVER FUEL LINE FITTINGS ARE LOOSENED OR DISCONNECTED, WRAP A SHOP CLOTH AROUND FITTING WHILE CONNECTING GAUGE, TO COLLECT FUEL. PLACE THE CLOTH IN AN APPROVED CONTAINER.

FUEL SYSTEM PRESSURE TEST

1. Remove air induction tube.

2. Connect fuel gage bar kit SA9127E (or equivalent) to fuel pressure test port.

3. Install bleed hose into an approved container and open shut off valve to bleed off any fuel in the system.

4. Close the fuel pressure gauge shut off valve.

5. If pressure bleeds off beyond specifications, install fuel return line plug, available in gauge bar kit.

6. Turn ignition key to the "ON" position (do not start engine) and record maximum pressure. Cycle the key "ON" and "OFF" several times to establish an accurate reading. Allow gage pressure to stabilize for thirty seconds. Refer to Specifications.

NOTE: The fuel pressure should be bled off and the test repeated a minimum of two times.

7. If the pressure does not leak down, replace the fuel pressure regulator.

8. If pressure does bleed off beyond specifications:

a. Check for fuel suction line leaks.

b. Perform fuel pump pressure test (return line plugged).

c. Perform fuel injector tip/leakage test.

NOTE: If the fuel pressure only bleeds off with the return line plugged, perform a fuel pump pressure test and check for leakage. If the fuel pump pressure does not bleed off, perform an injector leakage pressure test. MFI engines require the fuel rail to be removed for an injector leak down test. The injector can be visually inspected for leakage with the system pressurized at a minimum of 400 kPa (58 psi).

9. Install bleed hose into an approved container and open shut off valve to bleed system pressure. Once pressure is bled, remove gage bar adapter from fuel pressure test port and install cap.

10. Turn ignition key to the "ON" position (do not start engine) and record pressure gauge maximum pressure. Cycle the key "ON" and "OFF" several times to establish an accurate reading. Allow gage pressure to stabilize for thirty seconds. Refer to Specifications.

NOTE: The fuel pressure should be bled off and the test repeated a minimum of two times.

NOTE: If a start/stall condition exist after the vehicle has set for ten hours or less, and fuel pressure readings are extremely low during previous testing, the engine should be warmed up and left to set overnight with a fuel pressure gage attached. Fuel pressure after ten hours should be approximately 7 kPa (1 psi). If minimal pressure has been maintained, refer to step 4.



SPECIFICATIONS


Minimum Pressure: 400 kPa (58 psi)

Maximum Leakdown (in 5 minutes):

^ New Vehicle: 41 kPa (6 psi) max

^ Service Limit: 55 kPa (8 psi) max