With Special Tool

TEST DESCRIPTION
Water contamination in the fuel system may cause driveability conditions such as hesitation, stalling, no start, or misfires in one or more cylinders. Water may collect near a single fuel injector at the lowest point in the fuel rail and cause a misfire in that cylinder. If the fuel system is contaminated with water, inspect the fuel system components for rust or deterioration.

Alcohol concentrations of 10 percent or greater in fuel can be detrimental to fuel system components. Alcohol concentrations may cause fuel system corrosion, deterioration of rubber components, and subsequent fuel filter restriction. Some types of alcohol are more detrimental to fuel system components than others. Ethanol is commonly used in gasoline, but in concentrations of no more than 10 percent. Some fuels, such as E85, contain a very high percentage of ethanol. Fuel with more than 10 percent ethanol may cause driveability conditions such as hesitation, lack of power, stalling, or no start.



TEST PROCEDURE

CAUTION: Wrap a shop towel around the fuel pressure connection in order to reduce the risk of fire and personal injury. The towel will absorb any fuel leakage that occurs during the connection of the fuel pressure gage. Place the towel in an approved container when the connection of the fuel pressure gage is complete.

1. Turn ON the J 44175 Fuel Composition Tester.
2. Verify the fuel composition tester is operational by measuring the AC frequency output with a DMM. Refer to Measuring Frequency in Diagnostic Aids. A frequency without a fuel sample in the test cell indicates that the tester is working correctly.
3. Install the fuel pressure gage.






4. Close the bleed valve on the fuel pressure gage.

IMPORTANT: It will be necessary to bleed the fuel pressure gage a few times in order to obtain an accurate fuel sample.

5. Place the bleed hose of the fuel pressure gage into the 100 ml (3.4 oz) beaker (2).
6. Command the fuel pump ON with a scan tool.
7. Slowly open the bleed valve on the fuel pressure gage, until an adequate fuel sample is obtained.
8. If water appears in the fuel sample, clean the fuel system and replace the fuel in the vehicle.






9. Pour the fuel sample from the beaker (1) into the J 44175 fuel composition tester, until the level of the fuel is at the top of each fuel test port (2).

IMPORTANT: Do not allow any substances other than gasoline, ethanol/gasoline blends, air, or acetone into the test ports of the fuel composition tester. Contaminants in the fuel composition tester could result in misdiagnosis.

10. Observe the diagnostic LEDs on the fuel composition tester. If the red fuel diagnostic LED is illuminated, a fuel contamination condition exists. Refer to Fuel System Cleaning.
11. Measure the output frequency of the fuel composition tester.

Fuel Composition Test Examples:

12. Subtract 50 from the reading on the DMM to obtain the percentage of alcohol in the fuel sample. Refer to the examples in the table.
13. If the fuel sample contains more than 15 percent ethanol, replace the fuel in the vehicle.