Firebird V8-305 5.0L (1982)
Fuel Injector: Description and Operation
The TBI unit is made up of two major castings: a throttle body with a valve to control air flow and a fuel body assembly with an integral pressure
regulator and fuel injector to supply the necessary fuel.
The TBI unit also includes an electronically operated device to control idle speed and a device which provides information regarding throttle valve
position.
The throttle body portion of the TBI unit contains several ports which generate vacuum signals for the EGR valve, MAP sensor and canister purge
system.
The fuel injector is a solenoid operated device controlled by the ECM. Incoming fuel is directed to the lower end of the injector assembly which
has a fine screen surrounding the injector inlet. When the ECM actuates the solenoid, the normally closed ball valve is lifted off its seat and
pressurized fuel is injected in a conical spray pattern at the walls of the throttle body bore above the throttle valve. Excess fuel passes through a
pressure regulator and returns to the fuel tank.
The fuel pressure regulator on all systems, and the fuel pressure compensator on the front TBI unit of the "Crossfire" injection system are serviced
as a unit with the fuel meter cover assembly and must not be interchanged from one unit to another.
