High pressure fuel is supplied by an electric pump in the fuel tank. Pressure is regulated by the fuel pressure regulator. The fuel injector is a solenoid operated device, controlled by the Powertrain Control Module (PCM), that meters pressurized fuel to a single engine cylinder. The PCM energizes the high-impedance (12.0 ohms) injector solenoid to open a normally closed ball valve. This allows fuel to flow into the top of the injector, past the ball valve, and through a director plate at the injector outlet.
The director plate has four machined holes that control the fuel flow, generating a spray of finely atomized fuel at the injector tip. Fuel from the injector tip is directed at the intake valve, causing the fuel to become further atomized and vaporized before entering the combustion chamber. An injector stuck partly open can cause a loss of pressure after engine shutdown. Consequently, long cranking times would be noticed on some engines. A leaking fuel pressure regulator can also cause this.