Throttle Body Injection

Model 700 TBI:

Model 700 TBI - Exploded View:

PURPOSE
The fuel injectors are solenoid activated, controlled by the ECM. The injector provides a precise amount of atomized fuel to the engine cylinder for combustion.

OPERATION
The ECM turns on the solenoids, 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 fuel pressure regulator before being returned to the fuel tank.

DIAGNOSTIC NOTES
An injector that is stuck partly open would cause loss of pressure after engine shut down, so long crank times would be noticed on some engines. Dieseling could also occur because some fuel could be delivered to the engine after the ignition is turned "OFF."