Fuel Injector
The fuel injector is mounted in the throttle body such that fuel is injected into the incoming air flow. When electric current is supplied to the injector, the armature and pintle assembly move a short distance against a spring, opening a small orifice at the end of the injector. Fuel supplied to the injector is forced around the pintle valve and through this opening, resulting in a fine spray of fuel. Since fuel pressure at the injector is kept constant, the volume of fuel injected is dependent only on the length of time that the injector is energized. See Fig 1 .
During engine start-up, the injector delivers an extra amount of fuel to aid in starting.