Fuel Injector Assembly
The PFI Fuel Injector assembly is a solenoid operated device, controlled by ECM, that meters pressurized fuel to a single engine cylinder. The ECM energizes injector solenoid, which raises pintle. This allows fuel to flow through an opening at end of injector and around tip of pintle, to generate a conical spray pattern of finely atomized fuel. The fuel is directed at intake valve, causing it to become further atomized and vaporized before entering combustion chamber.
An injector that is stuck partly open would cause loss of fuel system pressure after engine shut down, so long crank times would be noticed on some engines. Dieseling could also occur because some fuel could be delivered to engine after ignition is turned "OFF".