Fuel Injector: Description and Operation

Fuel Injector:

The Sequential Multiport Fuel Injection (SFI) fuel injector is a solenoid operated device controlled by the PCM The PCM energizes the solenoid which opens a valve to allow fuel delivery.

The fuel is injected under pressure in a conical spray pattern at the opening of the intake valve. Excess fuel not used by the injectors passes through the fuel pressure regulator before being returned to the fuel tank.

When the PCM energizes the injector coil, a normally closed valve ball (4) opens, allowing fuel to flow past a director plate (5) to the injector outlet.

A fuel injector which is stuck partly open will cause a loss of fuel pressure after engine shut down, causing long crank times to be noticed on some engines.