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Home >> Chevrolet >> 2000 >> Tracker 4D Utility, 4WD, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics >> Diagnostic Tests >> DTC P0451: Fuel Tank Pressure Sensor Performance >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
  2. Retrieve DTCs. If DTC P0443, P0440, P0445 or P0450 is also set, diagnose affected DTC(s). If only DTC P0451 is set, go to next step.
  3. Turn ignition off. Remove fuel filler cap. Turn ignition on, with engine off. Observe fuel tank pressure sensor parameter on scan tool. If scan tool displays 0.0-0.5 in. H2 O (0.0-0.9 mm Hg), go to step  12. If scan tool does not display 0.0-0.5 in. H2 O (0.0-0.9 mm Hg), go to next step.
  4. Remove fuel tank. Remove fuel tank pressure sensor from fuel tank. Visually inspect fuel tank pressure sensor air vent hole and air pressure inlet passage for blockage. If blockage exists, go to step  21. If blockage does not exist, go to next step.
  5. Turn ignition on, with engine off. Disconnect fuel tank pressure sensor harness connector. Using DVOM, check voltage at fuel tank pressure sensor harness connector terminal No. 3 (reference voltage circuit). If voltage reading is 5 volts, go to step  7. If voltage reading is not 5 volts, go to next step.
  6. Check for an open or short in reference voltage circuit between fuel tank pressure sensor and PCM. Repair as necessary. After repairs, go to step  29. If circuit is okay, go to step  25.
  7. Using a test light connected to battery voltage, probe fuel tank pressure sensor harness connector terminal No. 2 (sensor ground). If test light illuminates, go to step  9. If test light does not illuminate, go to next step.
  8. Check for an open in sensor ground circuit between fuel tank pressure sensor and PCM. Repair as necessary. After repairs, go to step  29. If circuit is okay, go to step  25.
  9. Select DC voltage scale on DVOM. Reconnect fuel tank pressure sensor harness connector. Using DVOM connected to ground, backprobe fuel tank pressure sensor harness connector terminal No. 1 (pressure input circuit). If voltage reading is 2.0-2.5 volts, leave DVOM connected and go to next step. If voltage reading is not 2.0-2.5 volts, go to step  26.
  10. Apply a small amount of vacuum to fuel tank pressure sensor while observing DVOM. If voltage drops, go to next step. If voltage does not drop, go to step  27.
  11. Check for an open in pressure input circuit between fuel tank pressure sensor and PCM. Repair as necessary. After repairs, go to step  29. If circuit is okay, go to step  25.
    12. WARNING: DO NOT breathe air through EVAP component tubes and hoses. Fuel vapors inside EVAP components may cause personal injury.
  12. Remove fuel tank pressure control valve. Blow air through valve from canister port (some resistance should be present). If air escapes from fuel tank port, go to next step. If air does not escape from tank port, go to step  28.
    13. NOTE: Fuel tank pressure control valve will not allow air to flow from tank side port to canister side port until pressure on tank side port exceeds.5 psi (.04 kg/cm2 ).
  13. Blow hard through fuel tank port of fuel tank pressure control valve. Air should escape from canister port. Apply 15 in. Hg of vacuum to vacuum port of fuel tank pressure control valve. With vacuum applied, blow gently through fuel tank port. Air should escape easily through canister port. If fuel tank pressure control valve operates as described, go to next step. If fuel tank pressure control valve does not operate as described, go to step  28.
  14. Turn ignition off. Disconnect vacuum hose from EVAP canister vent solenoid canister port. Apply 15 in. Hg of vacuum to EVAP canister vent solenoid canister port. If solenoid holds vacuum, go to step  22. If solenoid does not hold vacuum, go to next step.
  15. Turn ignition on, with engine off. Using scan tool, command EVAP canister vent solenoid on. Apply 15 in. Hg of vacuum to EVAP canister vent solenoid canister port. If solenoid holds vacuum, go to next step. If solenoid does not hold vacuum, go to step  17.
  16. While EVAP canister vent solenoid is holding vacuum, use scan tool to command solenoid off. If vacuum is released, see DIAGNOSTIC AIDS . If vacuum is not released, go to step  24.
  17. Turn ignition off. Disconnect EVAP canister vent solenoid harness connector. Turn ignition on, with engine off. Using a test light connected to ground, probe EVAP canister vent solenoid harness connector terminal No. 1 (ignition positive voltage circuit). If test light illuminates, go to next step. If test light does not illuminate, go to step  19.
  18. Using scan tool, command EVAP canister vent solenoid on. Using a test light connected to battery voltage, probe EVAP canister vent solenoid harness connector terminal No. 2 (control circuit). If test light illuminates, go to step  23. If test light does not illuminate, go to step  20.
  19. Repair open or short in ignition positive voltage circuit between main relay and EVAP canister vent solenoid. After repairs, go to step  29.
  20. Check for an open in control circuit between EVAP canister vent solenoid and PCM. Repair as necessary. After repairs, go to step  29. If circuit is okay, go to step  25.
  21. Clean fuel tank pressure sensor air passage. After repairs, go to step  29.
  22. Check EVAP canister vent solenoid vacuum hoses for restriction. Repair as necessary. After repairs, go to step  29. If vacuum hoses are okay, go to next step.
  23. Replace EVAP canister vent solenoid. After replacing solenoid, go to step  29.
  24. Check for a short to ground in control circuit between EVAP canister vent solenoid and PCM. Repair as necessary. After repairs, go to step  29. If circuit is okay, go to next step.
  25. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step  29.
  26. Check for a short in pressure input circuit between fuel tank pressure sensor and PCM. Repair as necessary. After repairs, go to step  29. If circuit is okay, go to next step.
  27. Replace fuel tank pressure sensor. After replacing sensor, go to step  29.
  28. Replace fuel tank pressure control valve. After replacing fuel tank pressure control valve, go to next step.
  29. After repairs, clear DTCs. Operate vehicle within FREEZE FRAME conditions that set DTC. Check for DTCs. If no DTCs are stored, repair is complete. If any DTCs are stored, diagnose DTC(s).
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