What is the purpose of a fuel metering unit (FMU) in certain engines?

• A. To deliver a fixed amount of fuel regardless of engine data.
• B. To measure fuel temperature for safety.
• C. To measure and regulate fuel flow based on engine data and deliver an accurate fuel amount to the metering components.
• D. To vent fuel vapors back to atmosphere.

Answer: (C)

The FMU’s role is to match fuel delivery to what the engine actually needs by using engine data to regulate how much fuel is sent to the metering components. It collects information such as engine speed, load, airflow, and pressures, and then adjusts the fuel flow so the metering devices (like injectors or metering valves) receive the precise amount required to maintain the correct air-fuel ratio. This allows smooth operation across idle, acceleration, and varying loads, and helps control emissions.

Delivering a fixed amount would not account for changing conditions, causing rich or lean mixtures. Measuring fuel temperature or venting vapors are separate concerns in the fuel system and do not define the FMU’s primary purpose.