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Home >> Saturn >> 2003 >> Ion 1 Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing >> Fuel Systems >> Alcohol/Contaminants-In-Fuel Diagnosis With Special Tool >> Test Procedure
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Test Procedure

NOTE: The numbers in parenthesis in the following steps correspond to numbered components in referenced figures.
  1. Turn ON Fuel Composition Tester (J 44175), or equivalent.
  2. Verify the fuel composition tester is operational by measuring the AC frequency output using a DVOM. A frequency without a fuel sample in the test cell indicates that the tester is working correctly.
    3. WARNING: Wrap a shop towel around the fuel pressure connection to reduce the risk of fire and personal injury. The towel will absorb any fuel leakage that occurs during the connection and disconnection of the fuel pressure gauge. Place the towel in an approved container when the connection of the fuel pressure gauge is complete.
  3. Install the Fuel Pressure Gauge (J 34730-1A), or equivalent, to fuel pressure service port connection. See Figure . Wrap a shop towel around the fitting while connecting the gauge to avoid spillage.
  4. Close the bleed valve on the fuel pressure gauge.
  5. Place the bleed hose (1) of the fuel pressure gauge into the 100 ml beaker (2). See Fig 1 .
  6. Command the fuel pump relay ON using a scan tool.
  7. Slowly open the bleed valve on the fuel pressure gauge, until an adequate fuel sample is obtained. Bleed the fuel pressure gauge a few times to obtain an accurate fuel sample from the vehicle being tested.
  8. If water appears in the fuel sample, clean the fuel system and replace the fuel in the vehicle. See FUEL SYSTEM CLEANING under FUEL SYSTEMS in REMOVAL & INSTALLATION - ION article.
    9. CAUTION: 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 composition tester could result in misdiagnosis.
  9. Pour the fuel sample from the beaker (1) into the fuel composition tester (3), until the level of the fuel is at the top of each fuel test port (2). See Fig 2 .
  10. Observe the diagnostic LEDs on the fuel composition tester. If the Red fuel diagnostic LED is illuminated, a fuel contamination condition exists. See FUEL SYSTEM CLEANING under FUEL SYSTEMS in REMOVAL & INSTALLATION - ION article.
  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. See FUEL COMPOSITION TEST EXAMPLES  table.
  13. If the fuel sample contains more than 10 percent ethanol, add gasoline to the fuel tank or replace the fuel in the vehicle.
FUEL COMPOSITION TEST EXAMPLES

Example Frequency - Hz Subtract 50 Ethanol Percent
A 50 -50 0
B 65 -50 15
C 129 -50 79
Fig 1: Bleeding Fuel Into Beaker
G00196157Courtesy of GENERAL MOTORS CORP.
Fig 2: Pouring Test Sample Into Fuel Composition Test
G00196158Courtesy of GENERAL MOTORS CORP.
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