Sierra 1500 4WD V8-6.0L (2007)
Important:
*
The fuel pump relay may need to be commanded ON a few times in order to obtain the highest possible fuel pressure.
*
DO NOT start the engine.
Command the fuel pump relay ON with a scan tool.
3. Observe the fuel pressure gage with the fuel pump commanded ON. The fuel pressure should be 345-414 kPa (50-60 psi).
‹› If the fuel pressure is not 345-414 kPa (50-60 psi), refer to Fuel System Diagnosis (with LMG, LC9, or LY6) Fuel System Diagnosis (FPCM).
See: Computers and Control Systems/Testing and Inspection/Component Tests and General Diagnostics See: Computers and Control
Systems/Testing and Inspection/Component Tests and General Diagnostics
4. Monitor the CH-48027 for one minute. The fuel pressure should not decrease more than 34 kPa (5 psi).
‹› If the fuel pressure decreases more than 34 kPa (5 psi), refer to Fuel System Diagnosis (with LMG, LC9, or LY6) Fuel System Diagnosis
(FPCM). See: Computers and Control Systems/Testing and Inspection/Component Tests and General Diagnostics See: Computers and
Control Systems/Testing and Inspection/Component Tests and General Diagnostics
5. Perform the Fuel Injector Balance Test with Special Tool or the Fuel Injector Balance Test with Tech 2.
Fuel Injector Balance Test with Special Tool
1. Set the amperage supply selector switch on the fuel injector tester to the Balance Test 0.5-2.5 amp position.
2. Connect the J 39021 to a fuel injector with a J 44602.
3. Command the fuel pump relay ON and then OFF three times with a scan tool. On the last command, as the fuel pressure begins to slowly degrade
and stabilize, select a fuel pressure within 34 kPa (5 psi) of the maximum pump pressure. Record this fuel pressure. This is the starting pressure at
which you will pulse each injector.
4. Command the fuel pump relay ON one more time and energize the fuel injector by depressing the Push to Start Test button on the J 39021 at the
previously selected pressure.
5. After the injector stops pulsing, select Min from the Display Mode and record the Min pressure.
Important: New test results will not be recorded if the Min/Max results are not cleared after each injector is tested.
6. Clear the Min/Max results.
7. Select Normal from the Display Mode.
8. Repeat steps 2 and 4 through 7 for each fuel injector.
9. Perform the Pressure Drop Calculation.
Fuel Injector Balance Test with Tech 2
1. Command the fuel pump relay ON and then OFF three times with a scan tool. On the last command, as the fuel pressure begins to slowly degrade
and stabilize, select a fuel pressure within 34 kPa (5 psi) of the maximum pump pressure. Record this fuel pressure. This is the starting pressure at
which you will pulse each injector.
2. With a scan tool, select the Fuel Injector Balance Test function within the Special Functions menu.
3. Select an injector to be tested.
4. Press Enter to prime the fuel system.
5. Energize the fuel injector by depressing the Pulse Injector button on the scan tool at the previously selected pressure.
6. After the injector stops pulsing, select Min from the Display Mode on the CH-48027 and record the Min pressure.
Important: New test results will not be recorded if the Min/Max results are not cleared after each injector is tested.
7. Clear the Min/Max results on the CH-48027.
8. Select Normal from the Display Mode on the CH-48027.
9. Press Enter on the scan tool to bring you back to the Select Injector screen.
10. Repeat steps 3 through 9 for each fuel injector.
11. Perform the Pressure Drop Calculation.
Pressure Drop Calculation
1. Subtract the minimum pressure from the starting pressure for one fuel injector. The result is the pressure drop value.
2. Obtain a pressure drop value for each fuel injector.
3. Add all of the individual pressure drop values except for the injector suspected of being faulty. This is the total pressure drop.
4. Divide the total pressure drop by the number of fuel injectors that were added together. This is 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,
E-85 only. All other engine, refer to Fuel Injector Cleaning.
