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Home >> Chevrolet >> 2001 >> Venture Base, Van Passenger >> Repair and Diagnosis >> External Pages >> Different car >> Section 26 (Engine Controls Self-Diagnostics - 5.0L & 5.7L) >> Diagnostic Tests >> DTC P0440: EVAP System - Large Leak >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2001 GMC Savana, 2001 Chevrolet RV Cutaway, 2001 Chevrolet Cutaway, and 2001 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing powertrain diagnostic system check, go to next step.
  2. If scan tool indicates DTC P0443 or DTC P0449 are also set, diagnose those codes first. See DTC P0443: EVAP PURGE SOLENOID CONTROL CIRCUIT  or DTC P0449: EVAP VENT SOLENOID CONTROL CIRCUIT . If scan tool does not indicate DTC P0443 or DTC P0449 are also set, go to next step.
  3. See COMPONENT LOCATIONS . Inspect EVAP system for the following conditions:
    • Loose, missing, or damaged service port dust cap and/or Schrader valve.
    • Loose, incorrect, missing or damaged fuel fill cap.
    • A damaged EVAP canister purge valve.
    • Disconnected, improperly routed, kinked, or damaged EVAP pipes and hoses.
    • A damaged EVAP canister vent valve or EVAP canister.

    If problem was found, repair as necessary. After repairs, go to step  19. If problem was not found, go to next step.

    4. NOTE: SERVICE BAY TESTS are available with Tech 2 scan tool and may not be available with after-market scan tools.
  4. Using scan tool, capture and record FREEZE FRAME/FAILURE RECORDS data and clear DTCs. Using scan tool, perform SERVICE BAY TEST in SPECIAL FUNCTIONS menu. If scan tool indicates service bay test passed, see DIAGNOSTIC AIDS . If scan tool did not indicate service bay test passed, go to next step.
    5. NOTE: The following steps require EVAP Pressure/Purge Diagnostic Station (J 41413) and Fuel Fill Cap Adaptor (J 41415). Always zero EVAP pressure and vacuum (in. H2O) gauges on EVAP pressure diagnostic station before proceeding with diagnosis.
  5. Install fuel fill cap adapter. Connect EVAP pressure/purge diagnostic station to fuel fill cap adapter. Turn ignition on, engine off. Using scan tool, seal EVAP system. Using EVAP pressure/purge diagnostic station, pressurize system to 5 in. H2O. Rotate EVAP pressure/purge diagnostic station rotary switch to OFF/HOLD position. If 5 in. H2O was obtained, go to next step. If 5 in. H2O was not obtained, go to step  9.
  6. Compare EVAP pressure/purge diagnostic station value to scan tool Fuel Tank Pressure (FTP) sensor value. If EVAP pressure/purge diagnostic station value is about scan tool value, go to next step. If EVAP pressure/purge diagnostic station value is not about scan tool value, go to step  13.
  7. Using EVAP pressure/purge diagnostic station, maintain EVAP system pressure at 5 in. H2O. Monitor pressure gauge on EVAP pressure/purge diagnostic station. Using scan tool, command EVAP canister purge valve to 50 percent. If EVAP system pressure decreases, go to next step. If EVAP system pressure does not decrease, go to step  10.
  8. Inspect vacuum source to EVAP purge valve for blockage, cuts, or disconnects. If problem was found, repair as necessary. After repairs, go to step  19. If problem was not found, see DIAGNOSTIC AIDS .
    9. NOTE: It may be necessary to partially lower fuel tank to inspect components located in upper portion of tank.
  9. Using EVAP pressure/purge diagnostic station, continuously pressurize EVAP system. Using Ultrasonic Leak Detector (J 41416), inspect for leaks in the following locations:
    • EVAP system purge pipe.
    • EVAP vapor pipe.
    • EVAP vent hose/pipe.
    • Fuel fill pipe/hose and fuel fill cap.
    • EVAP canister.
    • EVAP canister vent valve.
    • EVAP canister purge valve.
    • Fuel sender assembly and/or seal.
    • Fuel Tank Pressure (FTP) sensor seal.
    • Fill limiter vent valve, pressure relief valve, rollover valves, permanent EVAP pipes and/or fuel tank.

    If leak was located and repaired, go to step  19. If leak was not located, see DIAGNOSTIC AIDS .

  10. Monitor pressure gauge on EVAP pressure/purge diagnostic station. Disconnect EVAP purge pipe from EVAP canister purge valve. If EVAP system pressure decreases, go to step  16. If EVAP system pressure does not decrease, go to next step.
  11. Monitor pressure gauge on EVAP pressure/purge diagnostic station. Disconnect purge pipe at EVAP canister. If EVAP system pressure decreases, go to step  17. If EVAP system pressure does not decrease, go to next step.
  12. Monitor pressure gauge on EVAP pressure/purge diagnostic station. Disconnect EVAP vapor line from EVAP canister. If EVAP system pressure decreases, go to step  18. If EVAP system pressure does not decrease, go to step  15.
  13. Using scan tool, monitor FTP sensor voltage. If FTP sensor voltage is more than 4.3 volts, see DTC P0453: FUEL TANK PRESSURE SENSOR - HIGH VOLTAGE . If FTP sensor voltage is not more than 4.3 volts, go to next step.
  14. Replace FTP sensor. After repairs, go to step  19.
  15. Repair pinched or obstructed EVAP vapor pipe between front and rear tanks. After repairs, go to step  19.
  16. Replace EVAP canister purge valve. After repairs, go to step  19.
  17. Repair restriction in EVAP purge pipe. After repairs, go to step  19.
  18. Replace EVAP canister. After repairs, go to step  19.
  19. Using scan tool, perform SERVICE BAY TEST in SPECIAL FUNCTIONS menu. If scan tool indicates service bay test passed, go to next step. If scan tool did not indicate service bay test passed, go to step  2.
  20. Using scan tool, observe stored information. If scan tool displays any DTCs that have not been diagnosed, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If scan tool does not display any DTCs, system is okay.
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