For 1990-2009 cars

Table 1: | Fuel Injector Balance Test Example (Actual Results May Vary)

(1) | First Reading
(2) | Second Reading

#### Fuel Injector Balance Test Example (Actual Results May Vary)

Cylinder | 1 | 2 | 3 | 4
--- | --- | --- | --- | ---
1st Reading | 379 kPa (55 psi) | 379 kPa (55 psi) | 379 kPa (55 psi) | 379 kPa (55 psi)
2nd Reading | 280 kPa (41 psi) | 310 kPa (45 psi) | 340 kPa (49 psi) | 317 kPa (46 psi)
Amount of Drop | 99 kPa (14 psi) | 69 kPa (10 psi) | 39 kPa (6 psi) | 62 kPa (9 psi)
Average Range: 47-87 kPa (6.8-12.6 psi) | Replace fuel injector - too much fuel pressure drop | Injector OK | Replace fuel injector - too little fuel pressure drop | Injector OK

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. The engine coolant temperature (ECT) must be below the operating temperature in order to avoid irregular fuel pressure readings due to Hot Soak fuel boiling.

2. If the pressure drop value for each fuel injector is within 20 kPa (3 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. Refer to the illustration above.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | Go to Diagnostic System Check - Engine Controls
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 is above 94°C (201°F). Install a scan tool. Does the scan tool indicate that the ECT Parameter is less than the specified value? | 94°C (201°F) | Go to Step 4 | --
4 |

1. Turn OFF the ignition.
2. Install the fuel pressure gauge. Refer to Fuel Pressure Gage Installation and Removal .
3. Turn ON the ignition, with the engine OFF.

Important:

• | It may be necessary to command the fuel pump ON a few times, in order to obtain the highest possible fuel pressure.

• | Do not start the engine.

4. Command the fuel pump ON with a scan tool.
5. Observe the fuel pressure gauge, with the fuel pump commanded ON.

Is the fuel pressure within the specified range?

364-405 kPa (53-59 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 fuel pressure gauge 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 6
6 |

1. Connect the J 39021 fuel injector tester to a fuel injector with a J 39021-380 fuel injector test harness.
2. Set the amperage supply selector switch on the fuel injector tester to the Balance Test 0.5-2.5 amp position.
3. Command the fuel pump ON and then OFF with a scan tool.

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.

4. Record the fuel pressure indicated by the fuel pressure gauge after the fuel pressure stabilizes. This is the first pressure reading.
5. Energize the fuel injector by depressing the Push to Start Test button on the fuel injector tester.
6. Record the fuel pressure indicated by the fuel pressure gauge after the fuel pressure gauge needle has stopped moving. This is the second pressure reading.
7. Repeat steps 1 through 6 for each fuel injector.
8. Subtract the second pressure reading from the first pressure reading for one fuel injector. The result is the pressure drop value.
9. Obtain a pressure drop value for each fuel injector.
10. Add all of the individual pressure drop values. This is the total pressure drop.
11. 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 | Replace the isolated fuel injector. Refer to Fuel Injector Replacement . Did you complete the repair? | -- | System OK | --