Fuel Injector: Description and Operation

MPFI Injector Assembly:

Fuel Injector Orientation:

PURPOSE
The fuel injector delivers a metered amount of fuel into the intake runner in a finely atomized conical spray pattern.

OPERATION
The Multi Port Fuel Injection (MPFI) injector assembly is a solenoid operated device, controlled by the Electronic Control Module (ECM), that meters pressurized fuel to a single engine cylinder.
The ECM energizes the injector solenoid, which opens a ball valve, allowing fuel to flow past the ball valve, and through a recessed flow director plate.
The director plate has six machined holes that control the fuel flow, generating a conical spray pattern of finely atomized fuel at the injector tip.
Fuel is directed at the intake valve, causing it to become further atomized and vaporized before entering the combustion chamber.

NOTE: An injector that is stuck partly open would cause loss of pressure after engine shut down. Consequently, long cranking 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".