On internal-combustion engines, a system that injects a precisely measured amount of fuel into the cylinder at exactly the right moment. Dispenses with the carburetor and increases engine efficiency. Fuel injection provides better metering of fuel and air than carburetors. This results in more power, improved fuel economy, and lower emissions. The simplest systems use single or dual injectors in a central chamber to supply all cylinders. More sophisticated systems use an injector at each cylinder to precisely meter fuel.Any system that meters fuel to an engine by measuring its needs and then regulating the fuel flow, by electronic or mechanical means, through a pump and injectors. Throttle-body injection locates the injector(s) centrally in the throttle-body housing, while port injection allocates at least one injector for each cylinder near its intake port.