Fuel Injector: Description and Operation

Notice: Numbers in text correspond to numbered components in image.

Fuel is delivered to the fuel inlet tube (2) of the fuel rail by the fuel pipes. The fuel then goes through the fuel rail to the fuel pressure regulator. The fuel pressure regulator maintains a constant fuel pressure at the fuel injectors. Remaining fuel is then returned to the fuel tank.

The Sequential Multiport Fuel Injection (SFI) fuel injector is a solenoid (3) operated device controlled by the PCM The PCM energizes the solenoid which opens a valve (1) to allow fuel delivery onto the director plate (2).

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.

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.