Express 3500 V8-6.0L (2010)
Component Testing
Fuel Injector Coil Test
Verify the resistance of each fuel injector with one of the following methods:
*
If the engine coolant temperature (ECT) sensor is between 10-32°C (50-90°F), the resistance of each fuel injector should be 11-14 ohms.
‹› If the injectors measure OK, perform the Fuel Injector Balance Test - Fuel Pressure Test.
‹› If not within the specified range, replace the fuel injector.
*
If the ECT sensor is not between 10-32°C (50-90°F), measure and record the resistance of each fuel injector with a DMM. Subtract the lowest
resistance value from the highest resistance value. The difference between the lowest value and the highest value should be equal to or less than 3
ohms.
‹› If the difference is equal to or less than 3 ohms, refer to Fuel Injector Balance Test - Fuel Pressure Test for further diagnosis of the fuel
injectors.
‹› If the difference is more than 3 ohms, add all of the fuel injector resistance values to obtain a total resistance value. Divide the total resistance
value by the number of fuel injectors to obtain an average resistance value. Subtract the lowest individual fuel injector resistance value from
the average resistance value. Compute the difference between the highest individual fuel injector resistance value and the average resistance
value. Replace the fuel injector that displays the greatest difference above or below the average.
Important:
*
DO NOT perform this test if the engine coolant temperature (ECT) is above 94°C (201°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.
*
Before proceeding with this test review the User Manual CH 48027-5 for Safety Information and Instructions.
Fuel Injector Balance Test-Fuel Pressure Test
1. Install a CH-48027. Refer to Fuel Pressure Gauge Installation and Removal (See: Fuel Pressure/Testing and Inspection/Fuel Pressure Gauge
Installation and Removal).
2. Turn ON the ignition, with the engine OFF.
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.
3. Command the fuel pump relay ON with a scan tool.
4. Observe the fuel pressure gauge 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 (Without FPCM) (See: Fuel Pump/Testing and
Inspection/Fuel System Diagnosis (Without FPCM)) Fuel System Diagnosis (FPCM) (See: Computers and Control Systems/Testing and
Inspection/Component Tests and General Diagnostics/Fuel System Diagnosis (FPCM)).
5. 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 (Without FPCM) (See: Fuel Pump/Testing and
Inspection/Fuel System Diagnosis (Without FPCM)) Fuel System Diagnosis (FPCM) (See: Computers and Control Systems/Testing and
Inspection/Component Tests and General Diagnostics/Fuel System Diagnosis (FPCM)).
6. 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, J 39021-210, and the J 39021-301 to the fuel meter body.
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.
