Fuel Injector
The fuel injector is located within the throttle body. The injector contains an electronically operated solenoid, plunger, spring loaded ball valve, valve seat and fuel spray nozzle. See Fig 1 . The injector is sealed in bore of the throttle body by an upper and lower "O" ring.
When the injector is energized by the ECU, the solenoid armature pulls the plunger upward allowing spring loaded ball valve to move off its seat. Fuel then flows through the spray nozzle. The injection pulse width is based on engine operating conditions, which are provided by the ECU. Volume of fuel injected is dependent only on length of time that injector is energized by ECU, as fuel pressure is constant at injector. During cold engine starts, extra fuel is supplied so richer mixture will aid in starting.