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Home >> Chevrolet >> 2021 >> Blazer RS, FWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 11 (Engine Controls And Fuel - 2.5L (LCV) - Diagnostic Information And Procedures (2 Of 2)) >> Diagnostic Information and Procedures >> Alcohol/Contaminants-in-Fuel Diagnosis >> Circuit/System Testing

Circuit/System Testing

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Alcohol in Fuel Testing with Special Tool, if Available

  1. Test the fuel composition using CH-44175 - A  and Instruction Manual.
  2. Verify no water appears in the fuel sample.
    • If water appears in the fuel sample 

      Clean the fuel system.

    • Go to next step: If no water appears in the fuel sample 
  3. Subtract 50 from the reading on the DMM in order to obtain the percentage of alcohol in the fuel sample.
  4. Verify the non-blended gasoline fuel sample does not measure greater than 15% or an E85 blended gasoline fuel sample measures greater than 91% ethanol.
    • If greater than the specified value 
    1. Add fresh regular gasoline to the vehicle's fuel tank.
    2. Remove a new sample of fuel from the tank.
    3. Test the fuel composition using CH-44175 - A  and Instruction Manual.
    4. Subtract 50 from the reading on the DMM in order to obtain the percentage of alcohol in the fuel sample.
    5. Verify the non-blended gasoline fuel sample does not measure greater than 15% or an E85 blended gasoline fuel sample measures greater than 91% ethanol.
      • If additional testing indicates that the ethanol percentage is still above 15% for a non-blended gasoline sample, drain and replace the vehicle's fuel. Refer to Fuel Tank Draining .
      • If additional testing indicates that the E85 blended gasoline sample still measures above 91%, continue adding fresh, regular gasoline until the ethanol content is 85% or less.
    • Go to next step: If the specified value or less 
  5. All OK.

Alcohol in Fuel Testing without Special Tool

    NOTE:

    This procedure is for non-blended gasoline only. If excessive alcohol content is suspected with E85 fuel add 15% tank volume of fresh, regular gasoline to the fuel tank.

  1. Using a 100 ml (3.38 oz) specified cylinder with 1 ml (0.034 oz) graduation marks, fill the cylinder with fuel to the 90 ml (3.04 oz) mark.
  2. Add 10 ml (0.34 oz) of water in order to bring the total fluid volume to 100 ml (3.38 oz) and install a stopper.
  3. Shake the cylinder vigorously for 10 - 15 s.
  4. Carefully loosen the stopper in order to release the pressure.
  5. Re-install the stopper and shake the cylinder vigorously again for 10 - 15 s.
  6. Put the cylinder on a level surface for approximately 5 min in order to allow adequate liquid separation. If alcohol is present in the fuel, the volume of the lower layer, which would now contain both alcohol and water, will be more than 10 ml (0.34 oz). For example, if the volume of the lower layer is increased to 15 ml (0.51 oz), this indicates at least 5% alcohol in the fuel. The actual amount of alcohol may be somewhat more because this procedure does not extract all of the alcohol from the fuel.
  7. Verify the non-blended gasoline fuel sample does not measure greater than 15%.
    • If greater than the specified value 
    1. Add fresh regular gasoline to the vehicle's fuel tank.
    2. Remove a new sample of fuel from the tank.
    3. Test the fuel composition of the new sample.
    4. Verify the non-blended gasoline fuel sample does not measure greater than 15%.
      • If greater than the specified value, drain and replace the vehicle's fuel. Refer to Fuel Tank Draining .
      • If the specified value or less, all OK.
    • Go to next step: If the specified value or less 
  8. All OK.

Particulate Contaminants in Fuel

  1. Using an approved fuel container, draw approximately 0.5 liter (0.53 qt) of fuel from the bottom of the fuel tank.
  2. Place the container on a level surface for approximately 5 min in order to allow settling of the particulate contamination. Particulate contamination will show up in various shapes and colors. Sand will typically be identified by a white or light brown crystals. Rubber will appear as black and irregular particles.
  3. Verify there are no physical contaminants or water present in the fuel sample.
    • If any physical contaminants or water are present 

      Clean the fuel system.

    • Go to next step: If no physical contaminants or water are present 
  4. All OK.
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