Fuel Injector: Testing and Inspection

The injectors inject fuel according to a signal coming from the ECM. The volume of fuel injected by the injector is determined by the time the solenoid valve is energized.

Circuit Diagram:

Harness Inspection Procedures:

Operation Sound Check
1. Using a stethoscope, check the injectors for a clicking sound at idle. Check that the sound is produced at shorter intervals as the engine speed increases.

NOTE: Be sure that the sound from an adjacent injector is not being transmitted along the delivery pipe to an inoperative injector.




2. If a stethoscope is not available, check the injector operation with your finger. If no vibrations are felt, check the wiring connector, injector, or injection signal from ECM.

Resistance Measurement Between Terminals




3. Disconnect the connector at the injector.
4. Measure the resistance between terminals.

Standard value: 15.9 ± 0.35 [at 20 °C (68 °F)]

5. If the resistance is not within specification, replace the injector.

Troubleshooting Procedures:

TROUBLESHOOTING HINTS
1. If the engine is hard to start when hot, check for fuel pressure and injector leaks.

2. If the injector does not operate when the engine is cranked, then check the following:
- Faulty power supply circuit to the ECM and faulty ground circuit
- Faulty MFI control relay
- Faulty crankshaft position sensor and camshaft position sensor

3. If there is any cylinder whose idle state remains unchanged when the fuel injection of injectors is cut one after another during idling, check for the following items about such cylinder.
- Injector and harness
- Ignition plug and high tension cable
- Compression pressure

4. If the injection system is OK but the injector drive time is out of specification, check for the following items.
- Poor combustion in the cylinder. (faulty ignition plug, ignition coil, compression pressure and etc.)

5. The MIL is on or the DTC is displayed on the SCAN TOOL under the following condition.
- When the injector itself is faulty