6 - Fuel Supply Leakdown Test

This test will determine if the fuel supply system, up to the fuel rail and injectors, will maintain pressure after the fuel pump is turned off.

NOTE: This test can be performed using the fuel pressure line quick-connect adapter (309728) or the fuel flow/pressure test adapter (SA9127E-7).

CAUTION: Do no not allow smoking or the use of open flames in the area where work on the fuel system is taking place. Anytime work is being done on the fuel system, disconnect the negative battery cable, except for those tests where battery voltage is required.

IMPORTANT: Battery must be at a minimum of 12 volts when performing any fuel system test. Charge battery before proceeding if below 12 volts




1. Remove air induction tube.

CAUTION: Whenever fuel line fittings are loosened or removed, wrap a shop cloth around the fitting and have an approved container available to collect any fuel.




2. Relieve fuel system pressure (refer to "Relieving Fuel Pressure.") Service and Repair
3. Remove fuel feed line retainer clip attachment screw (10 mm hex)




4. Disconnect fuel feed line at fuel rail.
a. Connect fuel feed line directly to pressure gauge using (309728) quick-connect adapter (3/8" x 1/4").

NOTE: To properly utilize the fuel flow/pressure test adapter it must always be connected with the fuel feed line on the "INLET" side of the adapter and the fuel return or drain line connected to the side with the flow control (ON/OFF) valve. If not connected properly, a "zero" pressure reading will always be read. Use the appropriately sized connector fittings to hookup the adapter to the feed and return lines.

b. If using the fuel flow/pressure test adapter, connect "INLET" to fuel feed line and assure that flow valve is OFF.




5. Connect pressure gauge to test adapter.
6. Energize fuel pump (refer to "Energizing the Fuel Pump") for a minimum of 10 seconds. Energizing the Fuel Pump
a. Record fuel pressure.
b. Repeat this procedure a minimum of two times.
7. Shut fuel pump OFF and wait 5 minutes.
8. Record fuel pressure and subtract from pressure recorded in step 6.
9. Compare pressure loss (decay) to published specification.
10. Refer to "Fuel System Diagnostic Chart" and use test result to make appropriate decision.