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Home >> Oldsmobile >> 2003 >> Bravada AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 249 (Engine Controls - System & Component Testing - 4.3L) >> Fuel Systems >> Alcohol/Contaminants In Fuel Diagnosis With Special Tool >> Diagnostic Procedures

Diagnostic Procedures

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  1. Turn on the Fuel Composition Tester (J-44175).
  2. 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.
  3. Install fuel pressure gauge.
    4. NOTE: Bleed fuel pressure gauge a few times in order to obtain an accurate fuel sample from the vehicle being tested.
  4. Close bleed valve on fuel pressure gauge.
  5. Place the bleed hose of the fuel pressure gauge into the 100 ml beaker.
  6. Using scan tool, command fuel pump relay on.
  7. Slowly open the bleed valve on the fuel pressure gauge, 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. 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.
  9. Pour fuel sample from the beaker into the tester until the level of the fuel is at the top of each fuel test port.
  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.
  12. Subtract 50 from the reading on the DVOM to obtain the percentage of alcohol in the fuel sample.
  13. If fuel sample contains more than 10 percent ethanol, add gasoline to the fuel tank or replace the fuel in the vehicle.
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