The scan tool is first used to energize the fuel pump relay. The fuel injector
tester is then used to pulse each injector for a precise amount of time, allowing
a measured amount of fuel into the manifold. This causes a drop in system fuel pressure
that can be recorded and used to compare each injector.
The numbers below refer to the step numbers on the diagnostic table.
Step
| Action
| Values
| Yes
| No
|
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 Solenoid Coil Test
|
3
|
Important : Do not perform this test if the engine coolant
temperature (ECT) is above 94°C (201°F).
Observe the ECT parameter with a scan tool.
Is the ECT parameter less than the specified value?
| 94°C (201°F)
| Go to
Step 4
| --
|
4
|
Important: Verify adequate fuel in the fuel tank before
proceeding with this diagnostic.
- Turn OFF the ignition.
- Install the
J 34730-1A
Fuel
Pressure Gage and the fuel pressure gage fitting. Refer to
Fuel Pressure Gage Installation and Removal
.
- Turn ON the ignition, with the engine OFF.
- Command the fuel pump relay ON with a scan tool.
Important:
| • | You may need to command the fuel pump relay ON a few times, in order to
obtain the highest possible fuel pressure. |
| • | Do not start the engine. |
- Observe the
J 34730-1A
with
the fuel pump relay commanded ON.
Is the fuel pressure within the specified range?
| 384-425 kPa (56-62 psi)
| Go to
Step 5
| Go to
Fuel System Diagnosis
|
5
|
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.
Monitor the
J 34730-1A
for
1 minute.
Does the fuel pressure decrease by more than the specified value?
| 34 kPa (5 psi)
| Go to
Fuel System Diagnosis
| Go to
Step 6
|
6
|
- Connect the
J 39021
Fuel
Injector Coil/Balancer Tester, the
J 39021-210
Injector Selector Switch Box, and the
J 39021-410
Fuel Injector Harness Adapter to the fuel injector multi-way connector.
- Set the amperage supply selector switch on the fuel injector tester to
the balance test 0.5-2.5 amp position.
- Command the fuel pump relay ON and then OFF with a scan tool.
- Record the fuel pressure indicated by the
J 34730-1A
after the fuel pressure stabilizes. This is the first pressure
reading.
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.
- Energize the fuel injector by depressing the Push to Start test button on the
fuel injector tester.
- Record the fuel pressure indicated by the
J 34730-1A
. This is the second fuel pressure reading.
- Repeat steps 1-6 for each fuel injector.
- Subtract the second pressure reading from the first pressure reading
for one fuel injector. The result is the pressure drop value.
- Obtain a pressure drop value for each fuel injector.
- Add all of the individual pressure drop values. This is the total pressure
drop.
- 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 more than the average
pressure drop or less than the average pressure drop by the specified value?
| 20 kPa (3 psi)
| Go to
Step 7
| Go to
Symptoms - Engine Controls
|
7
| Clean the fuel injectors. Refer to
Fuel Injector Cleaning
.
Did you complete the action?
| --
| Go to
Step 8
| --
|
8
| Operate the vehicle in order to verify the repair.
Does a driveability condition still exist?
| --
| Go to
Symptoms - Engine Controls
| System OK
|
