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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 385 (ENGINE CONTROLS - SYSTEM & COMPONENT TESTING - 3.4L)FUEL SYSTEMSFUEL TANK LEAK TESTDIAGNOSTIC PROCEDURE
2003 Chevrolet TrailBlazer 4.2 S, 4WD

Diagnostic Procedure

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Diagnostic Procedure
WARNING: This page is about a different car, the 2003 Pontiac Grand Am, 2003 Oldsmobile Alero, 2003 Chevrolet Monte Carlo, and 2003 Chevrolet Impala. 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 in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. After performing diagnostic system check - engine controls, go to next step.
    2. CAUTION: Place a dry chemical (Class B) fire extinguisher nearby before performing any on-vehicle service procedures. Failure to follow these precautions may result in personal injury.
  2. Raise and support the vehicle. Check the fuel tank and fuel pipes for damage or external leaks. Did you find fuel leaking from the fuel tank? If yes, go to step  7. If no, go to next step.
  3. Turn ignition switch to RUN position, engine OFF. Command the fuel pump ON using a scan tool. Check for fuel leaking from the fuel pipes. Did fuel leak from the fuel pipes? If yes, go to step  8. If no, go to next step.
  4. Install the Fuel Tank Cap Adaptor (J 41415-40). Connect the Evaporative Emissions System Tester (EEST) (J 41413-200) to the fuel tank cap adaptor. Seal the EVAP system using a scan tool. Do not exceed 15 in. H2O. Pressurize the fuel tank the EEST. Did fuel leak from the fuel tank? If yes, go to step  7. If no, go to next step.
    5. NOTE: The fuel tank may need to be partially lowered.
  5. Maintain pressure in the fuel tank using the EEST. Using the Ultrasonic Leak Detector (J 41416), test for leaks above the fuel level in the following locations:
    • The fuel tank, fill limiter vent valve, pressure relief valve and rollover valve.
    • The fuel sender housing and fuel sender seal.
    • The FTP sensor seal.
    • The fuel fill pipe and hose.

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

  6. Repair the system as necessary. Did you complete the repair? If yes, system is okay at this time.
  7. Replace the fuel tank. Did you complete the repair? If yes, system is okay at this time.
  8. Replace the leaking fuel pipe. Did you complete the repair? If yes, system is okay at this time.
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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.