Component Testing

Fuel Injector Balance Test with Special Tool

1. Ignition ON, with a scan tool verify that the engine coolant temperature (ECT) is less than 94°C (201°F).
   • If the ECT is greater than 94°C (201°F) allow the engine to cool before proceeding.
2. Ignition OFF, install the fuel pressure gage. Refer to Fuel Pressure Gage Installation and Removal .
3. Ignition ON, verify the fuel pressure is within 380-402 kPa (55-58 psi).
   • If the fuel pressure is not within the specified range refer to Fuel System Diagnosis  for further diagnosis of the fuel system.
4. Monitor the fuel pressure gage for 1 minute. Verify that the fuel pressure does not drop more than 34 kPa (5 psi).
   • If the fuel pressure decreases more than 34 kPa (5 psi) refer to Fuel System Diagnosis  for further diagnosis of the fuel system.
NOTE: Do Not repeat any portion of this test before running the engine in order to prevent the engine from flooding.
5. Connect the J 39021  to a fuel injector with the amperage supply selector switch on the fuel injector tester to the Balance Test 0.5-2.5 amp position.
6. Command the fuel pump relay ON with a scan tool and record the fuel pressure indicated by the fuel pressure gage after the fuel pressure stabilizes. This is the first pressure reading.
IMPORTANT:
• Repeat this step for each fuel injector in order to obtain a pressure drop value for each fuel injector.
• The fuel pressure may rise after the fuel injector stops pulsing. Record the fuel pressure value immediately after the fuel injector stops pulsing. DO NOT record the higher fuel pressure value.
7. Energize the fuel injector by depressing the Push to Start Test button on the fuel injector tester. Record the fuel pressure indicated by the fuel pressure gage after the fuel injector has stopped pulsing. This is the second pressure reading.
8. Add all of the individual pressure drop values in order to calculate the total pressure drop. Divide the total pressure drop by the number of fuel injectors in order to calculate the average pressure drop. The difference between any individual pressure drop and the average pressure drop should not be more than 20 kPa (3 psi).
   • If the difference between any individual pressure drop and the average pressure drop is more than 20 kPa (3 psi), replace the fuel injector.