Fuel Injector: Description and Operation

Fuel System Description

Fuel System Overview

Description and Operation


Fuel Rail Assembly





The fuel rail assembly attaches to the engine intake manifold. The fuel rail assembly performs the following functions:

* Positions the injectors (2) in the intake manifold
* Distributes fuel evenly to the injectors
* Integrates the fuel pressure regulator with the fuel metering system

Fuel Injectors





The Multec 3.5 fuel injector assembly is a solenoid operated device, controlled by the engine control module (ECM), that meters pressurized fuel to a single engine cylinder. The ECM energizes the high-impedance (12 ohms) injector solenoid (2) to open a normally closed ball valve (3). 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 it 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.

Fuel Metering Modes of Operation

Description and Operation