Fuel Injector: Description and Operation

TBI Unit:

PURPOSE
Sprays measured, highly atomized fuel into the intake manifold.

LOCATION AND ID
Two injectors are located in bore of Model 220 TBI unit.

OPERATION
The B+ circuit is supplied via the ECM relay. B- circuit is triggered on and off by the ECM. The ECU triggers the negative circuit on and off rapidly. The ECM controls the "ON" time (injector duration) for the injector based on calculations made within its memory.

When the ECM energizes the solenoid, a normally closed ball lifts off it's seat. Pressurized fuel is injected in a conical spray pattern against the walls of the throttle bore above the throttle valve.

Excess fuel, which is not needed by the injector, passes through the pressure regulator before returning to the fuel tank.

CONSTRUCTION
The model 220 TBI uses two electro-mechanical injectors designed with the flow capacity necessary for proper engine operation under all operating conditions.