Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of an injector.
All compression-ignition (diesel) engines use fuel injection, and many Spark-ignition engines use fuel injection of one kind or another. In automobile engines, fuel injection was first volume-produced in the late 1960s, and gradually gained prevalence until it had largely replaced carburetors by the early 1990s. The primary difference between carburetion and fuel injection is that fuel injection atomizes the fuel through a small nozzle under high pressure, while a carburetor relies on suction created by intake air accelerated through a Venturi tube to draw the fuel into the airstream.
The central task of a fuel injection system is to supply the correct amount of fuel for the combustion process inside an engine. System design and configuration affects and takes account of a variety of factors, including:
Engine performance and vehicle driveability (ease of starting, smooth running, etc)
Diagnostic provisions and ease of service
Ability to run on various fuels