Fuel Injector: Description and Operation

TBI Assembly:

Throttle Body Injection Assembly:

The fuel injector is solenoid activated, controlled by the ECM. The ECM turns on the solenoid, which lifts a normally closed ball off a seat. Fuel, under pressure, is injected in a conical spray pattern at the walls of the throttle body bore above the throttle valve.
The fuel that is not used by the injectors passes through the pressure regulator before being returned to the fuel tank.