Fuel Injector: Description and Operation

PURPOSE
The fuel injectors supply a precise amount of atomized fuel to the intake system.

CONSTRUCTION
The injectors consist of a fuel filter (screen), needle valve, solenoid, magnetic winding and the electrical connector for the ECM.

OPERATION
The ECM grounds the electrical circuit to operate the injectors. The needle valve solenoid opens when the magnetic winding is energized.

The injectors open and close sequentially once per firing cycle during normal engine operation.

The air/fuel mixture is controlled by injection duration, which determines the amount of atomized fuel injected into the intake system.

SIGNAL
Power is supplied to the fuel injectors via a thermal fuse. A separate output stage (switching unit), located inside the Engine Control Module, is provided for each fuel injector. The output stages are used to complete a ground circuit for the injectors. Multiple output stages are necessary for sequential injection and fault diagnosis.