Alcohol-In-Fuel

DIAGNOSIS
Alcohol-in-fuel can be detrimental to fuel system components and may cause driveability problems such as hesitation, lack of power, stalling, no start, etc. These conditions may be due to fuel system corrosion and subsequent fuel filter plugging, deterioration of rubber components and/or air-fuel mixture leaning.

Various types and concentrations of alcohol are used in commercial fuel. Some alcohol is more detrimental to fuel system components than others. If an excessive amount of alcohol in the fuel is suspected as the cause of a driveability problem, the following procedure may be used to detect its presence. This procedure uses water to extract the alcohol from the fuel, but the specific type of alcohol contamination cannot be determined from this test.

Testing Procedure
The fuel sample should be drawn from the bottom of the fuel tank so that any water present in the tank will be detected. The sample should be bright and clear. If the sample appears to be cloudy, or contaminated with water (as indicated by a water layer at the bottom of the sample), this procedure should not be used and the fuel system should be cleaned. For fuel system cleaning procedures, refer to "Fuel System Cleaning" later in this section.

1. Using a 100 ml cylinder with 1 ml graduation marks, fill with fuel sample to the 90 ml mark.

2. Add 10 ml of water to bring the total fluid volume to 100 ml and install a stopper.

3. Shake vigorously for 10 to 15 seconds.

4. Carefully loosen the stopper to release pressure.

5. Close the stopper and shake vigorously again for 10 to 15 seconds.

6. Put the graduated cylinder on a level surface for approximately 5 minutes 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) would be greater than 10 ml.

For example, if the volume of the lower layer is increased to 15 ml, it will indicate at least 5% alcohol in the fuel. The actual amount of alcohol may be somewhat greater because this procedure does not extract all of the alcohol from the fuel.