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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 143 (ENGINE CONTROLS - SYSTEM & COMPONENT TESTING)EMISSION SYSTEMS & SUB-SYSTEMS (GASOLINE)FUEL TANK LEAK TESTDIAGNOSTIC PROCEDURES
2003 Chevrolet TrailBlazer 4.2 S, 4WD

Diagnostic Procedures

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Diagnostic Procedures
WARNING: This page does not describe the selected car, but rather 31 other vehicles, including the 2002 Saturn Vue, 2002 Pontiac Montana, 2002 Pontiac Aztek, 2002 Oldsmobile Silhouette, and 2002 Oldsmobile Bravada. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article.
    2. NOTE: Before performing this procedure, place a dry chemical (class B) fire extinguisher near work area.
  2. Raise vehicle. Inspect fuel tank and fuel pipes for damage or external leaks. Did you find fuel leaking from fuel tank? If yes, go to step  7. If no, go to next step.
  3. Turn ON the ignition, with the engine OFF. With scan tool, command fuel pump ON. Inspect for fuel leaking from fuel pipes. Did fuel leak from fuel pipes? If yes, go to step  8. If no, go to next step.
  4. Install Fuel Tank Cap Adapter (J 41415-40). Connect EVAP Pressure/Purge Diagnostic Station (J 41413) to fuel tank cap adapter. With scan tool, seal EVAP system. DO NOT exceed 15 in. H2 O. With EVAP pressure/purge diagnostic station, pressurize fuel tank. Did fuel leak from fuel tank? If yes, go to step  7. If no, go to next step.
    5. NOTE: Fuel tank may need to be partially lowered during this step.
  5. With EVAP pressure/purge diagnostic station, maintain pressure in fuel tank. With Ultrasonic Leak Detector (J 41416), test for leaks above fuel level in following locations:
    • Fuel tank, fill limiter vent valve, pressure relief valve and rollover valves.
    • Fuel sender housing and fuel sender seal.
    • Fuel Tank Pressure (FTP) sensor seal.
    • EVAP vapor pipes.
    • Fuel fill pipe and hose.

    Did you locate a fuel leak? If yes, go to next step. If no, see DIAGNOSTIC AIDS .

  6. Repair system as necessary. After repairs, system is okay.
  7. Replace fuel tank. After repairs, system is okay.
  8. Replace leaking fuel pipe. After repairs, system is okay.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.