Component Tests and General Diagnostics

NOTE: A 100 ml cylinder, with 1 ml graduation marks, is needed to perform this test.

Purpose
Certain driveability complaints such as hesitation, lack of power, stall, no start, etc. may be caused by an excessive amount of alcohol in the fuel. The complaints may be due to fuel system corrosion and subsequent fuel filter plugging.

Excessive alcohol also causes deterioration of rubber components (such as O-rings), and corrodes injector tips.

Various types and concentrations of alcohol are used in commercial gasoline. Some alcohols are 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 condition, the following procedure may be used to detect the presence of alcohol in the fuel.

NOTE: In this procedure water is used to extract the alcohol from the fuel. However, the specific type of alcohol (Methyl Tertiary Butyl Ether (MTBE), Ethanol or Methanol) will not be determined by this procedure.

Procedure
1. Draw a fuel sample 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 cloudy, or contaminated with water (as indicated by a layer at the bottom of the sample), this procedure should not be used, and the fuel system should be cleaned.

2. Fill cylinder to the 90 ml mark.
3. Add 10 ml of water to bring the total fluid volume to 100 ml and install a stopper.
4. Shake vigorously for 10 to 15 seconds.
5. Carefully loosen the stopper to release pressure.
6. Close the stopper and shake vigorously again for 10 to 15 seconds.
7. Put the cylinder on a level surface, and let stand for approximately 5 minutes, (to allow adequate liquid separation).
- If the volume of the lower layer is now greater than 10 ml, alcohol is present in the fuel.

EXAMPLE: If the volume of the lower layer has increased to 15 ml, (an increase of 5 ml), there is at least 5 percent 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.

Acceptable standards for the following types of alcohol fuels are:

Methyl Tertiary Butyl Ether (MTBE) 11% by volume
Ethanol 10% by volume
Methanol 5% by volume