LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Cadillac >> 2003 >> Seville SLS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing >> Fuel Systems >> Fuel Tank Leak Test >> Diagnostic Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic Procedure

NOTE: Evaporative Emissions System Tester (J-41413-200), Fuel Tank Cap adapter (J-41415-40) and Ultrasonic Leak Detector (J-41416) are required for this procedure. See Figure -Figure .
  1. Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 4.6L DEVILLE & SEVILLE article.
    2. NOTE: Before performing this procedure, place a dry chemical (class B) fire extinguisher near the work area.
  2. Raise the vehicle. Inspect 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  6 . If no, go to next step.
  3. Turn ON the ignition, with the engine OFF. Using a scan tool, command the fuel pump ON. Inspect for fuel leaking from the fuel pipes. Did fuel leak from the fuel pipes? If yes, go to step  7 . If no, go to next step.
  4. Install the Fuel Tank Cap Adapter. Connect the Evaporative Emissions System Tester (EEST) to the fuel tank cap adapter. Using a scan tool, seal the EVAP system. DO NOT exceed 15 in. H2O. Using the EEST, pressurize the fuel tank. Did fuel leak from the fuel tank? If yes, go to step  6 . 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, test for leaks above the fuel level in the following locations.
    • The fuel tank, fill limiter vent valve, pressure relief valve and rollover valves.
    • The fuel sender housing and fuel sender seal.
    • The Fuel Tank Pressure (FTP) sensor seal.
    • The EVAP vapor pipes.
    • The fuel fill pipe and hose.

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

  6. Replace the fuel tank. See FUEL TANK under FUEL SYSTEMS in REMOVAL & INSTALLATION - DEVILLE & SEVILLE article. After repair is completed, go to step  8
  7. Replace the leaking fuel pipe. Repair as necessary. After repair is completed, go to next step.
  8. Operate the vehicle in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, go to DIAGNOSTIC AIDS  .
scientia non olet · About LEMON Manuals