Fuel InjectorsModes of Operation

The fuel injectors are pulse width modulated (PWM) solenoids controlled by the engine control module (ECM). The ECM turns ON the fuel injectors in order to open a normally closed ball or pintle valve. This allows fuel to flow into the top of the fuel injectors, past the ball or pintle valve, and through a recessed flow director plate at the injector outlet. The fuel rail is mounted on the intake manifold and distributes the fuel to each cylinder through the individual fuel injectors. The fuel rail consists of 3 parts:

• The pipe that carries fuel to each injector
• The fuel pressure test port (If Equipped)
• Individual fuel injectors

The director plate has machined holes that control the fuel flow, generating a conical spray pattern of finely atomized fuel at the fuel 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 partially stuck open may cause the following symptoms:

• Loss of fuel pressure with ignition OFF
• Extended crank time
• Dieseling