Fuel Injector(s)
Fuel injector is a solenoid controlled by ECM. Fuel is supplied at lower end of injector by fuel delivery system. Pressure to injector is maintained at 9-13 psi (.6-.9 kg/cm2 ) by the pressure regulator. Excess fuel passes through pressure regulator and is returned to fuel tank. Battery voltage is supplied to the injector when the ignition is on. ECM energizes solenoid by providing a ground path through its internal circuitry. This creates a magnetic field in the injector windings, causing the normally closed ball valve to lift off its seat. Fuel under pressure is injected in a conical spray pattern at walls of throttle bore, above throttle valve.
During engine cranking, fuel injector is pulsed (activated) once for each ignition reference pulse received by ECM. This is referred to as synchronized mode. In non-synchronized mode, injector is pulsed once every 6.25-12.5 milliseconds, depending upon engine calibration and operating conditions. In this mode, pulse is totally independent of distributor reference pulses.
On the 5.0L and 5.7L model 220 TBI units, 2 injectors are used in the throttle body. Injectors are alternately sprayed, using ignition module reference pulses.