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Home >> Chevrolet >> 1998 >> Venture Base, Van Cargo Extended >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P0440 - EVAP System >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. After performing OBD system check, go to next step.
  2. Check if DTC P1665 or P1676 is also set. If any of DTCs is present, diagnose affected DTCs. If DTCs are not present, go to next step.
  3. Turn ignition off. Remove fuel filler cap. Turn ignition on. Using scan tool, observe fuel tank pressure. If fuel tank pressure is zero in. H2O, go to next step. If fuel tank pressure in not zero in. H2O, diagnose evaporative system.
  4. Replace fuel filler cap. Using scan tool, capture FAIL RECORD data for DTC P0440 and clear DTC. Command EVAP vent solenoid on. Connect EVAP Pressure/Purge Diagnostic Station (J 41413) to EVAP service port. Pressurize EVAP system using diagnostic station. Monitor pressure on EVAP pressure gauge on diagnostic station. If pressure is 5 in. H2O, go to next step. If pressure is not 5 in. H2O, go to step 6).
  5. Maintain EVAP pressure at 5 in. H2O. Observe fuel tank pressure on scan tool. If fuel tank pressure reading on scan tool is 5 in. H2O, go to step 8). If reading is not 5 in. H2O, go to next step.
  6. Disconnect fuel tank vapor line and EVAP purge line from EVAP canister. Block canister fitting for fuel tank pressure line. Connect a hand-held vacuum pump to canister fitting for EVAP purge line. Ensure that EVAP vent solenoid is still commanded on. Apply vacuum to EVAP canister. If vacuum can be maintained at 5 in. Hg, go to step 11). If vacuum cannot be maintained at 5 in. Hg, go to step 10).
  7. Check for restriction in fuel tank vapor line or EVAP purge line. Repair as necessary. After repairs, go to step 16). If restriction is not found, diagnose EVAP system.
  8. Disconnect vacuum source line at EVAP purge solenoid and plug vacuum source fitting on solenoid. Using scan tool's output tests function, select and activate SYSTEM PERF. Pressurize EVAP system to 5 in H2O. Observe EVAP pressure gauge on diagnostic station while removing plug from EVAP purge solenoid vacuum source fitting. If EVAP pressure decreases to zero in. H2O within 15 seconds while system performance is activated, go to next step. If EVAP pressure does not decrease to zero in. H2O within 15 seconds, go to step 13).
  9. Install vacuum gauge on EVAP diagnostic station to vacuum source line. Start and operate engine to greater than 2000 RPM. Observe source vacuum level. If vacuum level is greater than -15 in. Hg, see DIAGNOSTIC AIDS. If vacuum level is not greater than -15 in. Hg, go to step 14).
  10. Check for disconnected or damaged vent hose. Check for damaged EVAP canister. Repair as necessary. After repairs, go to step 16). If no problems are found, go to next step.
  11. Check for faulty or missing fuel filler cap. Check for disconnected or leaking fuel tank vapor line. Check for disconnected or damaged EVAP purge line. If problem is found, repair as necessary. After repairs, go to step 16). If no problems are found, go to next step.
  12. Using scan tool, command EVAP vent solenoid on. Continuously attempt to pressurize the EVAP system by leaving the EVAP diagnostic station control knob in the pressurized position. Using the Ultrasonic Leak Detector (J 41416), locate and repair leak in EVAP system. After repairs, go to step 16).
  13. Replace EVAP purge solenoid. After replacing solenoid, go to step 16).
  14. Check for carbon release into the EVAP system. Repair as necessary. After repairs, go to step 16).
  15. Replace EVAP vent solenoid. After replacing solenoid, go to next step.
  16. Turn ignition on. Using scan tool, command EVAP vent solenoid on. Using EVAP diagnostic station, pressurize EVAP system to 15 in. H2O. Move rotary switch in diagnostic station to HOLD and observe EVAP pressure gauge. If EVAP pressure decreases to less than 10 in. Hg within 2 minutes, repeat step 3). If EVAP pressure does not decrease, system is okay.
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