Diagnostic Procedures

The fuel sample should be drawn from the bottom of the fuel tank, because any water present in the tank will be concentrated there. The fuel sample should be bright and clear. If the sample appears to be cloudy or contaminated with the water, as indicated by a water layer at the bottom of the sample, this procedure should not be used. The fuel system should be cleaned.

1. Using a 100 ml cylinder with 1 ml graduation marks, fill cylinder 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 on cylinder.
3. Shake vigorously for 10 to 15 seconds.
4. Carefully loosen the stopper to release pressure.
5. Close stopper and shake cylinder vigorously again for 10 to 15 seconds.
6. Put the graduated cylinder on a level surface for about 5 minutes to allow adequate time for liquid to separate.

If there is alcohol present in the fuel, the volume of the lower layer, which will now contain both alcohol and water, will be more than 10 ml. For example, if volume of the lower layer is increased to 15 ml, this will indicate that there is at least 5 percent 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.