2005 Hummer H2 4D Utility PickupFACTORY OEM SERVICE PROCEDURE

Test Description

The number below refers to the step number on the diagnostic table.

  1. 5:  If the pressure drop value for each fuel injector is within 10 kPa (1.5 psi) of the average pressure drop value, the fuel injectors are flowing properly. Calculate the pressure drop value for each fuel injector by subtracting the second pressure reading from the first pressure reading.
Fuel Injector Balance Test with Tech 2

Step Action Values Yes No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module (PCM) Connector End Views
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2 Did you perform the Fuel Injector Coil Test? - Go to Step 3  Go to Fuel Injector Coil Test 
3
IMPORTANT:
  • Do not perform this test if the engine coolant temperature (ECT) is above 94°C (201°F).
  • Verify there is adequate fuel in the fuel tank before proceeding with this diagnostic.
  1. Turn OFF the ignition.
  2. Turn OFF all accessories.
  3. Install the fuel pressure gage. Refer to Fuel Pressure Gage Installation and Removal .
  4. Turn ON the ignition, with the engine OFF.
  5. Command the fuel pump ON with a scan tool.
    6. IMPORTANT:
    • You may need to command the fuel pump ON a few times in order to obtain the highest possible fuel pressure.
    • Do not start the engine.
  6. Observe the fuel pressure gage, with the fuel pump commanded ON.
Is the fuel pressure within the specified value?		 385-425 kPa (55-62 psi) VIN: (V, T, U) Gasoline
335-375 kPa (48-54 psi) VIN: Z Ethanol		 Go to Step 4  Go to Fuel System Diagnosis 
4
IMPORTANT: The fuel pressure may vary slightly when the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabilize and remain constant.
Observe the fuel pressure gage for 1 minute.Does the fuel pressure drop more than the specified value?		 34 kPa (5 psi) Go to Fuel System Diagnosis  Go to Step 5 
5 
NOTE: Refer to Fuel Injector Balance Test Notice .
  1. Select the Fuel Injector Balance Test function with a scan tool.
  2. Select an injector to be tested.
  3. Press Enter. This will prime the fuel system.
  4. Record the fuel pressure indicated by the fuel pressure gage after the fuel pressure stabilizes. This is the 1st pressure reading.
    5. IMPORTANT: Record the fuel pressure value immediately after the fuel injector stops pulsing. The fuel pressure may rise after the fuel injector stops pulsing. Do not record the higher fuel pressure value.
  5. Energize the fuel injector by depressing the Pulse Injector button on the scan tool. This will energize the injector and decrease the fuel pressure.
  6. Record the fuel pressure indicated by the fuel pressure gage after the fuel injector has stopped pulsing. This is the 2nd pressure reading.
  7. Press Enter again to bring you back to the Select Injector screen.
  8. Repeat for each fuel injector.
  9. Subtract the 2nd pressure reading from the 1st pressure reading for one fuel injector. The result is the pressure drop value.
  10. Obtain a pressure drop value for each fuel injector.
  11. Add all of the individual pressure drop values. This is the total pressure drop.
  12. Divide the total pressure drop by the number of fuel injectors. This is the average pressure drop.
Does any fuel injector have a pressure drop value that is either higher than the average pressure drop or lower than the average pressure drop by the specified value?		 20 kPa (3 psi) Go to Step 6  Go to Symptoms - Engine Controls 
6 Replace the fuel injector. Refer to Fuel Injector Replacement .
Did you complete the replacement?		 - Go to Step 7  -
7 Operate the vehicle in order to verify the repair.
Does a driveability condition still exist?		 - Go to Symptoms - Engine Controls  System OK
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.