Fuel Injector: Description and Operation

Fuel Injector:

The fuel injector nozzles are electro-mechanical devices which meter and atomize fuel delivered to the engine. The injectors are mounted in the lower intake manifold and positioned so that their tips are directing fuel just ahead of the engine intake valves.
This specialized solenoid has an armature and a needle or ball valve with a spring that holds the needle or ball closed against the valve seat. The armature opens the valve when it receives a current pulse from the system computer. When the solenoid is energized, it unseats the valve to inject fuel. The injector always opens the same distance, and the fuel pressure is maintained at a constant value by the pressure regulator. The amount of fuel delivered by the injector depends on the amount of time that the nozzle is open. This is the injector pulse width: the time in milliseconds that the nozzle is open.
An electrical signal from the Electronic Control Assembly (ECA) activates the injector solenoid causing the pintle to move inward off the seat, allowing fuel to flow through the orifice. Atomization of the fuel is obtained by contouring the pintle at the point at where the fuel separates.