Fuel Injector: Description and Operation

Fuel Injector Location:

FUNCTION
The fuel injectors are solenoid operated valves that deliver fuel, in a metered amount, to the combustion chambers of individual cylinders.

OPERATION
When the solenoid coil is energized (on), the plunger is retracted lifting the needle valve off its seat, allowing fuel to be injected into the combustion chamber. When the solenoid is de-energized (off) spring pressure closes the valve.

This vehicle uses bottom fed fuel injectors. The bottom of the injector is fed with fuel from a passage in the intake manifold.

The ASD relay supplies voltage to the fuel injectors. The PCM and ICM control ground paths to fuel injectors, by switching the ground path on and off. The PCM and ICM can fine tune fuel delivery adjusting injector pulse width (on time). The PCM controls injectors 2,3,4,6,7,8,9,and 10. The ICM controls injectors 1 and 5, according to PCM instructions.

CIRCUIT OPERATION
Power for the fuel injectors is supplied on circuit A142 when the contacts in the Automatic Shut Down (ASD) relay are CLOSED. Battery voltage for the contact side is supplied on circuit A14. This circuit is HOT at all times and protected by a fusible link located near the auxiliary jumper post on the left toe box.

Power for the coil side of the ASD relay is supplied on circuit A21. This circuit is HOT when the ignition switch is in the START or RUN position. Ground for the coil side of the relay is controlled by the Powertrain Control Module (PCM) on circuit K51.

When the PCM supplies a ground path for circuit K51 the contacts in the ASD relay close connecting circuits A14 and A142. Circuit A142 powers the fuel injectors and is double crimped at the ASD relay to supply an ASD relay energized input to the PCM.

The PCM and the Ignition Control Module (ICM) control the ground path for the injectors as follows:
- Circuit K11 is the ground circuit for Injector # 1. Circuit K11 connects to cavity 12 of the ICM.
- Circuit K12 is the ground circuit for Injector # 2. Circuit K12 connects to cavity 16 of the PCM.
- Circuit K13 is the ground circuit for Injector # 3. Circuit K13 connects to cavity 14 of the PCM.
- Circuit K14 is the ground circuit for Injector # 4. Circuit K14 connects to cavity 18 of the PCM.
- Circuit K38 is the ground circuit for Injector # 5. Circuit K38 connects to cavity 6 of the ICM.
- Circuit K58 is the ground circuit for Injector # 6. Circuit K58 connects to cavity 13 of the PCM.
- Circuit K26 is the ground circuit for Injector # 7. Circuit K26 connects to cavity 58 of the PCM.
- Circuit K28 is the ground circuit for Injector # 8. Circuit K28 connects to cavity 38 of the PCM.
- Circuit K5 is the ground circuit for Injector # 9. Circuit K5 connects to cavity 15 of the PCM.
- Circuit K8 is the ground circuit for Injector # 10. Circuit K8 connects to cavity 17 of the PCM.