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Home >> Chevrolet >> 2021 >> Blazer RS, FWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 11 (Engine Controls And Fuel - 2.5L (LCV) - Diagnostic Information And Procedures (2 Of 2)) >> Diagnostic Information and Procedures >> Fuel Injector Diagnosis >> Fuel Injector Balance Test

Fuel Injector Balance Test

WARNING: This page is about a different variant/trim than selected.
NOTE:
  • DO NOT perform this test if the engine coolant temperature (ECT) is above 60°C (140°F). Irregular fuel pressure readings may result due to hot soak fuel boiling.
  • Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic.

Fuel Injector Balance Test with Active Fuel Injector Tester - Preferred Method

  1. Verify the battery is fully charged and all accessories are OFF.
  2. Ignition OFF, all vehicle systems OFF. It may take up to 2 min for all vehicle systems to power down. Install CH-47976  and CH-47976-500  . Connect CH-47976 - 503  and CH-47976 - 512  to CH-47976-500  .
    3. NOTE:
    • Important that voltage is jumped to the correct fuse terminal.
    • Not all (KL9) vehicle are affected. Only vehicles listed below require this jumper step.
  3. For applications with Start/Stop (KL9), battery voltage must be jumped to the low/negative side of the fuse for the KR27 Starter Relay using a 3 amp fused jumper wire. Reference below to determine the appropriate fuse to remove for your application.
    • Cruze (LE2) - Fuse F16UA, Fuse 16, "Fuel Injection"
    • Envision (LCV / LTG) - Fuse F3UA, Fuse F03, "NON/WALK"
    • Equinox/Terrain (LYX / LTG) - Fuse F3UA, Fuse 3, "Lambda 1"
    • Malibu (LFV / LKN / LTG) - Fuse F76UA, Fuse 76, "PWR/TRN OFF Engine"
    • Regal (LGX / LTG) - Fuse F46UA, Fuse 46, "ECM IGN"
  4. Turn ON the Active Fuel Injector Tester and select the vehicle.
  5. Ignition ON, perform the Injector Test with the Active Fuel Injector Tester.
    • If the Active Fuel Injector Tester aborts testing due to incorrect fuel pressure or fuel leak down 

      Refer to Fuel System Diagnosis .

    • Go to next step: If the Active Fuel Injector Tester does not abort testing 
  6. Compare the test results with the appropriate recommended tolerance.
    • If any fuel injector exceeds the recommended tolerance 

      Replace the appropriate Q17 Fuel Injector(s).

    • Go to next step: If all fuel injectors are within the recommended tolerance 
  7. All OK.

Fuel Injector Balance Test with Scan Tool

  1. Verify the correct low side fuel pressure. Refer to Fuel System Diagnosis .
  2. Engine idling, verify the scan tool Fuel Rail Pressure Sensor parameter is approximately 3 MPa (435 PSI).
    3. NOTE:

    The engine speed must be between 600 - 1000 RPM to perform this test.

  3. Select the Fuel Injector Balance function within the Control Functions menu of a scan tool.
  4. Select and test an injector. Repeat for each injector.
  5. Obtain and record a pressure drop value for each injector.
  6. Add all of the individual pressure drop values except for the injector suspected of being faulty. This is the total pressure drop.
    7. NOTE:

    For engines with 2 banks of cylinders, only measure average pressure drop on cylinders that are on the same bank.

  8. Divide the total pressure drop by the number of fuel injectors that were added together. This is the average pressure drop.
  9. Multiply the average pressure drop by 0.20. This is the acceptable variance from the average pressure drop, 20 percent.
  10. Verify the difference between any individual pressure drop and the average pressure drop is not greater than the acceptable variance.
    • If greater than the acceptable variance 

      Replace the Q17 Fuel Injector.

    • Go to next step: If within the acceptable variance 
  11. All OK.
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