Certain driveability complaints such as hesitation, lack of power, stall, no start, etc. may be caused by an excessive amount of alcohol in fuel. The complaints may be due to fuel system corrosion and subsequent fuel filter plugging, deterioration of rubber components such as internal fuel pump module O-rings and/or air-fuel mixture leaning effects.

Various types and concentrations of alcohols are used in commercial gasoline. Some alcohols are more damaging to fuel system components than others. If an excessive amount of alcohol in the fuel is suspected as the cause of a driveability condition, the following procedure may be used to detect the presence of alcohol in the fuel. In this procedure, water is used to extract the alcohol from the fuel. However, the specific type of alcohol is not determined.

The fuel sample should be drawn from the bottom part of the tank so that any water, if already present, can be detected. The sample should be bright and clear. If the sample appears cloudy or contaminated with water as indicated by a water layer on the bottom part of the sample, this procedure should not be used. The entire test should be repeated at least twice. The fuel system should then be cleaned, refer to Fuel System Cleaning .

Caution: Do not allow smoking or the use of open flames in the area where work on the fuel or EVAP system is taking place. Anytime work is being done on the fuel system, disconnect the negative battery cable, except for those tests where battery voltage is required.

Important: This test can be performed using the SA9213NE Gas Check Tester, or equivalent.

1. Using a 100 ml cylinder with 1 ml graduation marks, fill with fuel 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. Carefully loosen the stopper to release the pressure.
4. Close the stopper and shake vigorously again for 10-15 seconds.
5. Carefully loosen the stopper to release the pressure.
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 alcohol and water will be greater than 10 ml. For example, if the volume of the lower layer is increased to 15 ml it would indicate at least 5 percent alcohol in fuel. The actual amount of alcohol may be somewhat greater because this procedure does not extract all of the alcohol from the fuel.