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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1024 (Engine Controls - 4.3L (Troubleshooting & Diagnosis)) >> Troubleshooting >> Alcohol/Contaminants-in-Fuel Diagnosis (With Special Tool) >> Test Procedure

Test Procedure

WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Test the fuel composition using J 44175  Fuel Composition Tester and J44175-3 Instruction Manual.
  2. If water appears in the fuel sample, perform the following steps:
    1. Clean the fuel system. Refer to Fuel System Cleaning .
    2. Replace the fuel filter. Refer to Fuel Filter Replacement .
  3. Subtract 50 from the reading on the DMM in order to obtain the percentage of alcohol in the fuel sample. Refer to the examples in the Fuel Composition Test Examples table.
  4. If the fuel sample contains more than 15 percent ethanol, add fresh, regular gasoline to the vehicle's fuel tank.
  5. Test the fuel composition.
  6. If testing shows the ethanol percentage is still more than 15 percent, replace the fuel in the vehicle. Refer to Fuel System Cleaning .
Fuel Composition Test Examples

- Frequency (Hz) Subtract 50 Ethanol Percent
Example A 50 Hz -50 0
Example B 65 Hz -50 15
Example C 129 Hz -50 79
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