Diagnostic Procedures
- Turn on the Fuel Composition Tester (J-44175).
- Verify the fuel composition tester is operational by measuring the AC frequency output with a DVOM. A frequency without a fuel sample in the test cell indicates that the tester is working correctly.
- Install fuel pressure gauge.
- Close bleed valve on fuel pressure gauge.
- Place the bleed hose of the fuel pressure gauge into the 100 ml beaker.
- Using scan tool, command fuel pump relay on.
- Slowly open the bleed valve on the fuel pressure gauge, until an adequate fuel sample is obtained.
- If water appears in the fuel sample, clean the fuel system and replace the fuel in the vehicle.
- Pour fuel sample from the beaker into the tester until the level of the fuel is at the top of each fuel test port.
- 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 .
- Measure the output frequency of the fuel composition tester.
- Subtract 50 from the reading on the DVOM to obtain the percentage of alcohol in the fuel sample.
- If fuel sample contains more than 10 percent ethanol, add gasoline to the fuel tank or replace the fuel in the vehicle.
NOTE:
Bleed fuel pressure gauge a few times in order to obtain an accurate fuel sample from the vehicle being tested.
NOTE:
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 tester could result in misdiagnosis.