Fuel Pressure/Leakdown Testing Activity

Fuel Pressure Testing and Leakdown Testing

1. With the ignition switch off, remove the fuel pump relay. Crank engine and run engine out of fuel. Do this several times to ensure fuel pressure has been reduced to 0 psi. Turn key back to off position.

2. Connect fuel pressure gauge from gauge set VP part # 3855533 with adapter VP part # 3862357 to the fuel pressure rail.

3. Using the special tool for fuel line removal, disconnect both the pressure and return lines to the fuel rail.

4. Install the fuel line shutoff adapters, (Kent Moore J 37287) between the disconnected fuel lines and the fuel rail. Note: when installing there should be an audible click as hoses go together. After click is heard, try to pull the connection apart. It should NOT come apart. If it does come apart, then it wasn’t installed properly or the connection is damaged.

WARNING: IF THIS CONNECTION COMES APART WHILE ENGINE IS RUNNING, A LARGE FUEL LEAK WILL OCCUR WITH A POSSIBLE FIRE RESULTING.

5. Ensure the valves in the J 37287 fuel shut off adapters are in the open position (in line with the hose).

6. Reinstall fuel pump relay. Turn ignition switch on several times to run the fuel pumps and refill the lines. Check for any fuel leaks.

7. After fuel pressure has built up, turn key off and observe fuel pressure. Fuel pressure should hold at 40 psi + or – 4 psi for an 8.1L or 50-60 psi for the 5.0L.

8. Close both valves in the fuel shutoff adapters and record fuel pressure. ______ PSI

9. Record fuel pressure after 2 minutes. _______ PSI Fuel pressure should drop very little. If fuel pressure were to drop 10 PSI in those 2 minutes, where would the leak be and how would you fix it? ______________________________________________________________________________

10. Open both shutoff valves and cycle the ignition switch to rebuild fuel pressure. Close the fuel shutoff valve in the supply line to the fuel rail. Observe and record the fuel pressure drop after 2 minutes. _______ PSI drop.

11. If pressure did not drop in step 9 and pressure drops in step 10, what is (are) the possible component(s) causing the pressure drop? ________________________________________________________________________

12. Open both shutoff valves and cycle the ignition switch to rebuild fuel pressure. Close the fuel shutoff valve in the return line from the fuel rail. Observe and record the fuel pressure drop after 2 minutes. _______ PSI drop.

13. If the pressure did not drop in steps 9 or 10 but does drop now. Where is the leak? ________________________________________________________________________