FUEL INJECTION

in an internal-combustion engine, introduction of fuel into the cylinders by means of a pump rather than by the suction created by the movement of the pistons. On diesel engines, which have no spark plugs, the heat created by compressing air in the cylinders ignites the fuel, which has been pumped as a spray into the heated air. In engines with spark ignition, fuel-injection pumps are often used instead of conventional carburetors. Fuel injection distributes the fuel more evenly to the individual cylinders than does a carburetor system, so that 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 a pumping action, fuel-injection systems are necessary.