Vehicle EVAP System Test
^ Before conducting the test the fuel and evaporative emission system should be checked for signs of damage or wear, i.e. fuel filler cap seal, pipes, connections etc. The fuel tank should be between 50% and 70% full.
^ Remove the fuel filler cap from the fuel tank filler neck and install it on the fuel cap test adapter receiver, (B, Illustration 3). The cap will act as a seal on the adapter receiver.
^ Install the fuel cap test adapter, (Illustration 4), on the filler neck.
^ At the PDU base station, load the PDU with disc PDU 1055 (replaces Service Action Disc 2.0).
^ Select Diagnostics from the main menu screen
^ Enter the vehicle details.
^ Select Toolbox from the main menu screen.
^ Select Evaporative System Leak Check from the toolbox menu screen. Select 4.0L engine size under vehicle features.
^ Follow the operator messages on the PDU screen. (Position the vehicle and switch off the ignition, select P apply parking brake).
^ Take the PDU, with the required data now loaded, and connect it to the vehicle.
^ The PDU will communicate with the ECM.
^ "TURN IGNITION ON" is displayed on the screen, switch on the ignition.
^ Press "ENTER".
^ The operator action screen with the instruction to set up the leak check equipment will display.
^ Select YES, if the canister close valve should be closed for the duration of the test.
^ A 30 minute count down will display on the screen.
Note:
The canister close valve will be closed for 30 minutes, after which time it will be automatically opened in order to protect the solenoid.
^ Turn lever to "A" TEST position.
^ Press ON/OFF switch to power up tester.
^ Turn the gas cylinder valve to the open position. Observe the warnings.
^ Turn the EVAP tester control valve, (B, Illustration 2), to the "B", FILL position.
^ Press the START switch and allow the 2 minute timer to cycle. After the timer has cycled, the SYSTEM PRESSURE digital display, (D, Illustration 2), should show 13.8 to 14.2 in. H2O.
^ If the reading is outside the limits then use the FINE PRESSURE ADJUSTMENT control knob, (E, Illustration 2), to bring the pressure within the limits.
^ If you cannot adjust the pressure to 13.8 to 14.2 in. H2O, the system has a leak. Use the ultrasonic leak detector to check for leakage in the vehicle's EVAP/fuel system.
^ Press the RESET button.
^ Turn the control valve, (B, Illustration 2), to the "A" TEST position.
^ Press the START button, (F Illustration 2), to begin the 2 minute countdown, which will be shown on the SYSTEM PRESSURE display.
^ Wait until the countdown is completed.
^ During the countdown any pressure lost will be shown on the PRESSURE LOSS digital display, (G, Illustration 2).
^ If the system has passed the test, the green PASSED light will be switched on.
^ If the system has failed the test, the red FAILED light will be switched on.
Note:
The PASS and FAIL limits are set within the tester and are not adjustable.
^ Place the manifold discharge hose in an approved safety container and then press the pressure discharge valve on the manifold to depressurize the system.
^ If the system has passed the test, the system should be retested to verify the first result.
^ If the system has failed the test, the system should be repressurized and investigated by the use of the ultrasound detector.
^ If a leak is detected, the fault should be rectified and the system retested.
^ If a leak is not detected, then the fault must be within the EVAP purge valve or the canister close valve.
^ Install a plug or a clamp on the pipe connecting the purge valve to the intake manifold and repeat the test.
^ If the system has passed the test, then the purge valve is leaking and it should be replaced by a new valve.
^ If the system has failed the test, then remove the plug or clamp and install it on the pipe connecting the canister close valve to the canister and then repeat the test.
^ If the system has passed the test, then the canister close valve is leaking and it should be replaced by a new valve.
Confirmation Check:
^ Close the canister close valve and run the system pressure test.
^ If the system has failed the test, the process detailed above must be repeated.
^ If the system has passed the test, the canister close valve should be opened and the pressure drop observed.
^ If the pressure does not drop rapidly after the canister close valve is opened then the running loss control valve is faulty and it should be removed and a new valve installed.
Note:
Always use the "ON/OFF" valve of the gas cylinder to cut off the gas flow when the tester is not in use.