fuel injection, system in an internal-combustion engine internal-combustion engine, one in which combustion of the fuel takes place in a confined space, producing expanding gases that are used directly to provide mechanical power.
..... Click the link for more information. that delivers fuel or a fuel-air mixture to the cylinders by means of pressure from a pump. It was originally used in diesel engines diesel engine, type of internal-combustion engine invented by the German engineer Rudolf Diesel and patented by him in 1892. Although his engine was designed to use coal dust as fuel, the diesel engine now burns low-cost fuel oil.
..... Click the link for more information. because of diesel fuel's greater viscosity and the need to overcome the high pressure of the compressed air in the cylinders. A diesel fuel injector sprays an intermittent, timed, metered quantity of fuel into a cylinder, distributing the fuel throughout the air within. Fuel injection is also now used in gasoline engines in place of a carburetor carburetor (kär`byərā`tər, –bə–)
..... Click the link for more information. . In gasoline engines the fuel usually is injected into the intake manifold and mixed with air, and the resulting mixture is delivered to the cylinder. Modern fuel injection systems use computers to regulate the process. Fuel injection results in more efficient fuel combustion, improving fuel economy and engine performance and reducing polluting exhaust emissions.

fuel injection

In an internal-combustion engine, introduction of fuel into the cylinders by a pump rather than by the suction created by the movement of the pistons (see piston and cylinder). On diesel engines, which lack spark plugs, the heat created by compressing air in the cylinders ignites the fuel, which has been pumped in as a spray. In engines with spark ignition, fuel-injection pumps are often used instead of conventional carburetors. Fuel injection distributes the fuel more evenly to the cylinders than does a carburetor; more power can be developed and undesirable emissions are reduced. In engines with continuous combustion, such as gas turbines and liquid-fueled rockets, which have no pistons to create suction, fuel-injection systems are necessary.