Definition
An engine fuel delivery system that meters fuel and sprays it directly into the intake port of each cylinder, rather than mixing it with air in a carburetor upstream. Fuel is pressurized and distributed through a fuel pump, fuel/air control unit, fuel manifold (distributor), and individual discharge nozzles at each cylinder. Air enters separately through the induction system and combines with the fuel just before entering the combustion chamber.
Plain English
Instead of mixing fuel and air in one place and sending the mixture to all the cylinders, a fuel injection system sprays a measured amount of fuel directly at each cylinder, and the air arrives separately. Each cylinder gets its own little fuel nozzle.
Context Anchor
Seen in engine and induction system discussions, aircraft operating handbooks, engine-start procedures, and troubleshooting for hard starting or rough engine operation.
Derivation
‘Inject’ comes from the Latin injicere, meaning ‘to throw in.’ The fuel is literally thrown (sprayed) into the intake stream rather than drawn in by suction as in a carburetor.
Why Pilots Care
It offers better fuel efficiency, eliminates carburetor icing, and maintains proper mixture at high altitudes or during aerobatic maneuvers.
Analogy
It is like a controlled spray system: instead of pouring fuel in, it measures the amount and sprays it where the engine can use it.
Intuition Check
Do not think of fuel injection as just “fuel going into the engine.” The key idea is controlled, measured fuel sprayed under pressure at the right place in the engine’s air path.
Example Sentence 1
Because the aircraft has a fuel injection system, the pilot followed the hot-start procedure in the POH instead of the normal priming sequence used on carbureted engines.
Example Sentence 2
During the high-altitude flight, the fuel injection system automatically adjusted the mixture to prevent the engine from running lean.