2500 4x2 Pickup V8-5.9L VIN Z (1994)
Fuel Injector: Description and Operation
Fuel Injector - Cutaway View
PURPOSE
The fuel injectors are solenoid operated valves that deliver fuel, in a metered amount, to the combustion chambers of individual cylinders.
OPERATION
The ASD relay supplies voltage to the fuel injectors. The Powertrain Control Module (PCM) energizes the fuel injectors, by switching the ground
path on. The PCM de-energizes the fuel injectors, by switching the ground path off.
When the solenoid coil is energized, the plunger is retracted lifting the needle valve off its seat, allowing pressurized fuel to be injected into the
combustion chamber. When the solenoid is de-energized spring pressure closes the valve.
The system fuel pressure is maintained, by the fuel pressure regulator, at 31 psi with vacuum applied to the fuel pressure regulator. The fuel
pressure will increase by 8 to 10 psi if no vacuum is applied at the fuel pressure regulator.
The amount of fuel that is injected is determined by the amount of time that the needle valve remains open. This time is commonly referred to as
the "pulse width" of the injector. The PCM varies the pulse width of the injector to fine tune the air/fuel mixture for changing engine operating
conditions.
NOTE: The fuel injector wiring harness has numbered tags attached to each injector connector, for ease of identification.