Fuel Injectors

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The fuel injector assembly is a solenoid operated device, controlled by the PCM, that meters pressurized fuel to a single engine cylinder. The PCM energizes the high-impedance (12 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. See Fig 1. 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.

Fig 1: Identifying Fuel Injector

Courtesy of GENERAL MOTORS CORP.