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Home >> Chevrolet >> 2003 >> Venture Base, Van Passenger Extended >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0440: EVAP System - Large Leak Detected >> Diagnostic Procedures

Diagnostic Procedures

  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Observe the Freeze Frame/Failure Records for this DTC. Using scan tool, perform the Service Bay Test. Does the scan tool indicate that the Service Bay Test passed? If yes, go to DIAGNOSTIC AIDS . If no, go to next step.
  3. Inspect the EVAP system for the following conditions:
    • Loose, missing, or damaged service port Schrader valve.
    • Loose, incorrect, missing, or damaged fuel fill cap.
    • A damaged EVAP canister purge valve.

    Raise vehicle on a hoist. Inspect the EVAP system for the following conditions:

    • Disconnected, improperly routed, kinked, or damaged EVAP pipes and hoses.
    • A damaged EVAP canister vent valve or EVAP canister.

    Did you find and correct the condition? If yes, go to step  20. If no, go to next step.

    4. NOTE: Ensure that vehicle underbody temperature is similar to the ambient temperature and allow the surrounding air to stabilize before starting the diagnostic procedure. System flow will be less with higher temperatures.
  4. Turn ignition off. Connect the Evaporative Emissions System Tester (J-41413-200) power supply clips to a known-good 12-volt source. Install the Fuel Tank Cap Adapter (J-41415-40) to the fuel fill pipe. Connect the fuel fill cap to the Fuel Tank Cap Adapter. Connect the Evaporative Emissions System Tester nitrogen/smoke supply hose to the Fuel Tank Cap Adapter. Turn ignition on, with engine off. Command the EVAP vent solenoid closed with a scan tool. Turn the nitrogen/smoke valve on the Evaporative Emissions System Tester control panel to SMOKE. Use the remote switch to introduce smoke into the EVAP system. Use the EVAP Service Port Vent Fitting (J-41413-VLV) to open the EVAP service port. Remove the EVAP Service Port Vent Fitting once smoke is observed. Continue to introduce smoke into the EVAP system for an additional 60 seconds. Inspect the entire EVAP system for exiting smoke with the High Intensity White Light (J-41413-SPT). Continue to introduce smoke at 15 second intervals until the leak source has been located. Did you locate and repair a leak source? If yes, go to step  19. If no, go to next step.
  5. Disconnect the Fuel Tank Cap Adapter from the fuel fill pipe. Install the fuel fill cap to the fuel fill pipe. Connect the Evaporative Emissions System Tester nitrogen/smoke supply hose to the EVAP service port. Use the remote switch to introduce smoke into the EVAP system. Inspect the entire EVAP system for exiting smoke with the High Intensity White Light. Continue to introduce smoke at 15 second intervals until the leak source has been located. Did you locate and repair a leak source? If yes, go to step  19. If no, go to next step.
  6. Use the remote switch to stop introducing smoke. Install the Fuel Tank Cap Adapter to the fuel fill pipe. Connect the Evaporative Emissions System Tester nitrogen/smoke supply hose to the Fuel Tank Cap Adapter. Connect the vehicle fuel fill cap to the Fuel Tank Cap Adapter. Command the EVAP vent solenoid open with a scan tool. Compare the Fuel Tank Pressure Sensor parameter, with a scan tool, to the Evaporative Emissions System Tester pressure/vacuum gauge. Is the scan tool Fuel Tank Pressure Sensor parameter within one in. H2O of the Evaporative Emissions System Tester pressure/vacuum gauge? If yes, go to next step. If no, go to step  16.
  7. Seal the EVAP system using the EVAP Purge/Seal function with a scan tool. Turn the nitrogen/smoke valve on the Evaporative Emissions System Tester control panel to NITROGEN. Use the Evaporative Emissions System Tester to pressurize the EVAP system to 10 in. H2O. Is the Fuel Tank Pressure Sensor parameter more than 5 in. H2O ? If yes, go to next step. If no, go to step  16.
  8. Use the remote switch to stop introducing nitrogen into the EVAP system. Increase the EVAP purge solenoid to 100 percent. Is the Fuel Tank Pressure Sensor parameter less than one in. H2O? If yes, go to DIAGNOSTIC AIDS . If no, go to next step.
  9. Disconnect the EVAP purge vacuum source from the EVAP purge solenoid. Is the Fuel Tank Pressure Sensor parameter less than one in. H2O? If yes, go to step  13. If no, go to next step.
  10. Disconnect the EVAP purge pipe from the EVAP purge solenoid. Is the Fuel Tank Pressure sensor parameter less than one in. H2O? If yes, go to step  17. If no, go to next step.
  11. Disconnect the EVAP purge pipe at the EVAP canister. Is the Fuel Tank Pressure Sensor parameter less than one in. H2O? If yes, go to step  15. If no, go to next step.
  12. Disconnect the EVAP vapor pipe at the EVAP canister. Is the Fuel Tank Pressure Sensor parameter less than one in. H2O? If yes, go to step  18. If no, go to step  14.
  13. Repair pinched or obstructed EVAP purge solenoid vacuum source. After repairs, go to step  19.
  14. Repair pinched or obstructed EVAP vapor pipe. After repairs, go to step  19.
  15. Repair restriction in the EVAP purge pipe. After repairs, go to step  19.
  16. Replace FTP sensor. See REMOVAL & INSTALLATION - MONTANA, SILHOUETTE & VENTURE article. After repairs, go to step  19.
  17. Replace EVAP canister purge valve. See REMOVAL & INSTALLATION - MONTANA, SILHOUETTE & VENTURE article. After repairs, go to step  19.
  18. Replace EVAP canister. See REMOVAL & INSTALLATION - MONTANA, SILHOUETTE & VENTURE article. After repairs, go to next step.
  19. Using scan tool, perform the Service Bay Test. Does the scan tool indicate that the Service Bay Test passed? If yes, go to next step. If no, go to step  33.
  20. Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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