What component delivers fuel directly into the combustion chamber in a modern engine? The answer is a fuel injector. A fuel injector is a precisely controlled nozzle that sprays pressurized fuel into an engine’s air stream or, in a direct-injection system, into the combustion chamber itself.
An injector is not the same as a carburetor. A carburetor uses the moving air stream and a pressure difference to draw fuel into the intake. Fuel injection instead meters fuel through an injector, often under electronic control from the engine control unit. The injector opens for a carefully timed interval, shaping the amount and pattern of the spray.
The wording “directly into the combustion chamber” describes direct injection specifically. Port-injected gasoline engines place injectors in the intake ports upstream of the valves, while gasoline direct-injection and many diesel systems inject into the chamber. Common-rail diesel systems use a high-pressure rail to supply several electronically controlled injectors.