Fuel Injector: Description and Operation

Fig. 4 Cross sectional view of fuel injector:

The fuel injector, Fig. 4, is an electro-mechanical type valve which controls fuel flow into the engine. The injector consists of a magnetic coil, a fuel metering plunger with a magnetic core, and a spring. Because each injector is connected to the system through the fuel pump relay, the injectors will open whenever they are provided a ground path by the ECU. When this occurs, the magnetic coil is energized, lifting the plunger off its seat and allowing fuel to enter the intake manifold.
After receiving inputs from various sensors, the ECU determines the correct injector pulse width and varies the length of time that the injector is provided with a ground path. In this way the ECU can supply fuel to meet all engine speed and load requirements.