What is the function of a float carburetor?

• A. It measures airflow and dispenses the appropriate amount of gasoline into the airflow and ensures the fuel is vaporized by ignition.
• B. It regulates ignition timing.
• C. It filters air entering the engine.
• D. It stores fuel until needed.

Answer: (B)

A float carburetor’s job is to store fuel in a small bowl and meter it into the airstream in exact amounts as air flows through the carburetor. The float rises with the fuel level and pushes a needle valve closed to stop more fuel from entering; as fuel is drawn out into the jets, the float drops and opens the valve again to maintain a steady level. This keeps a ready supply of fuel for mixing with incoming air in the venturi, so the engine gets the right air-fuel mixture.

Ignition timing isn’t controlled by the carburetor, so regulating when sparks fire is outside its function. It also doesn’t filter the air. The true role is storing fuel in the bowl and metering it as needed to form the correct mixture.