Fuel Cut-Off Mode

No fuel is delivered by the fuel injectors when the ignition is OFF. This prevents dieseling or engine run-on. Also, the fuel is not delivered if there are no reference pulses received from the central power supply. This prevents flooding.

Fuel Injector Description 

The Multiport Fuel Injection (MFI) assembly is a solenoid-operated device controlled by the engine control module (ECM). It meters pressurized fuel to a single engine cylinder. The ECM energizes the fuel injector or the solenoid to a normally closed ball or pintle valve. This allows fuel to flow into the top of the injector, past the ball or pintle valve, and through a recessed flow director plate at the injector outlet.

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 from the tip is directed at the intake valve, causing it to become further atomized and vaporized before entering the combustion chamber. A fuel injector which is stuck partially open will cause a loss of fuel pressure after the engine is shut down. Also, an extended crank time will be noticed on some engines. Dieseling can also occur because some fuel can be delivered to the engine after the ignition is turned OFF.