For 1990-2009 cars

Table 1: | Example
Table 2: | Injector Flow/Voltage Drop Check

### Circuit Description

The Injector Flow/Voltage Drop Check compares the fuel pressure drop when each injector is pulsed for a set amount of time. Since each injector pulses the same, the fuel pressure drop for each injector should be approximately the same. Any of the suspect fuel injectors can be identified by either a too high or a too low fuel pressure drop. This check also determines if the voltage drop of the injector is within specification. Injector voltage drop out of specification can cause driveability conditions that are intermittent or that do not show up during an injector flow check. This chart requires the J 34730-91 Fuel Pressure Gauge, the J 39200 Voltmeter and the J 39021 Fuel Injector Tester.

### Test Description

The number(s) below refer to the step number(s) on the Diagnostic Table.

1. Caution: Wrap a shop towel around the fuel pressure connection in order to reduce the risk of fire and personal injury. The towel will absorb any fuel leakage that occurs during the connection of the fuel pressure gage. Place the towel in an approved container when the connection of the fuel pressure gage is complete.

   The first second of the voltage displayed by the DVM may be inaccurate due to the initial current surge, therefore, record the lowest voltage displayed by the DVM after the first second of the test. The voltage that is displayed by the DVM should be within the specified range (refer to the example). The voltage that is displayed by the DVM may increase throughout the test as the fuel injector windings warm and the resistance of the fuel injector windings changes. An erratic voltage reading (large fluctuations in the voltage that do not stabilize) indicates that there is an intermittent connection within the fuel injector.

#### Example

Resistance Ohms | Voltage Specification at 10°C-35°C (50°F-95°F)
--- | ---
16-17 | 7.75-8.75
Fuel Injector Number | Voltage Reading | Pass/Fail
1 | 8.3 | P
2 | 8.1 | P
3 | 8.0 | P
4 | 8.1 | P
5 | 6.5 | F
6 | 8.5 | P

#### Injector Flow/Voltage Drop Check

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain OBD System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Connect the scan tool.
2. Check the engine coolant temperature.

Is the engine coolant temperature within the specified limits?

10°C-35°C (50°F-95°F)

Go to Step 3

--

3 |

1. Turn off the ignition.

Notice: In order to prevent flooding of a single cylinder and possible engine damage, relieve the fuel pressure before performing the fuel injector coil test procedure.

2. Relieve the fuel pressure. Refer to the Fuel Pressure Relief .
3. Access the fuel injector electrical connectors as required.
4. Connect the J 39021 fuel injector tester to B+ and ground.
5. Set the amperage supply selector switch on the fuel injector tester to the Coil Test 0.5 amp position.
6. Connect the leads from the J 39200 Digital Volt Meter (DVM) to the fuel injector tester. Refer to the illustration associated with the test description.
7. Set the DVM to the tenths scale (0.0).

Important: Check the engine coolant temperature again to ensure that the correct chart is being used.

8. Connect the fuel injector tester to a fuel injector.
9. Press the Push to Start Test button on the fuel injector tester.

Important: The voltage reading may rise during the test.

10. Observe the voltage reading on the DVM.
11. Record the lowest voltage that is observed after the first second of the test.
12. Repeat steps 8 through 11 for each fuel injector.

Did any fuel injector have an erratic voltage reading (large fluctuations in voltage that do not stabilize) or a voltage reading outside the specified limits?

7.75-8.75V

Go to Step 4

Go to Fuel Injector Balance Test

4 | Replace the malfunctioning fuel injector(s). Refer to the Fuel Injector and Fuel Rail Replacement . Is the replacement complete? | -- | Go to Fuel Injector Balance Test | --