How does a fuel-injected engine meter fuel?

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Fuel metering in an injected engine is driven by matching the amount of fuel to the amount of air entering the engine. The fuel metering units are controlled by an intricate system (usually the engine control unit with sensors) that measures air mass flow and engine operating conditions. This setup calculates the exact fuel amount needed and delivers it through injectors, keeping the air–fuel ratio correct across different speeds and loads. The float chamber is a feature of carburetors, not fuel-injection systems, and fuel quantity isn’t determined by spark timing or by pump speed alone. So the system delivering fuel in proportion to air mass flow through metering units controlled by the aircraft’s fuel-management system is the correct concept.