What is another type of fuel metering system used on reciprocating engines other than carburetors?

• A. Direct fuel injection.
• B. Diaphragm pump.
• C. Electronic throttle control.
• D. Pneumatic metering.

Answer: (A)

Fuel metering means delivering the right amount of fuel to match the air entering the engine so the mixture is at the optimal ratio for combustion. Direct fuel injection is a system that meters fuel with precision and injects it directly into the cylinder (or very near the intake valve) using injectors controlled by the engine’s control system. This replaces a carburetor’s venturi-based metering and gives per-cylinder, real-time control of the fuel amount, improving efficiency, power, and emissions across a wide range of operating conditions.

The other options don’t provide the metering function in the same way: a diaphragm pump moves fuel but does not regulate the amount delivered; electronic throttle control manages air flow by moving the throttle electronically (often used with fuel injection, but not the fuel metering itself); pneumatic metering isn’t a standard, widely used fuel metering method for reciprocating engines.