In a closed-feed injection carburetor, how is fuel metered?

• A. Through fixed jets according to airflow
• B. By servo pressure
• C. By variable jets controlled by RPM
• D. Not metered

Answer: (A)

In a closed-feed injection carburetor, fuel metering is done by fixed jets that admit a precise amount of fuel into the intake air as it flows through the venturi. The airflow creates a suction that pulls fuel through these fixed jets, so the amount of fuel delivered follows the amount of air moving through the system. Because the jets are fixed in size, there isn’t a servo regulator or jets that change with RPM in this design; the metering relies on the venturi-induced suction to regulate fuel flow. This is why fixed jets according to airflow is the correct way this system meters fuel.