How does a float-type carburetor meter fuel?

• A. It uses electronic sensors to meter fuel.
• B. It meters fuel based on throttle position alone.
• C. It uses a float-controlled chamber and venturi to regulate fuel flow based on air intake.
• D. It uses a hydraulic pump to meter fuel.

Answer: (C)

The fuel is metered by a float-controlled chamber that sits in the float bowl, which is connected to the fuel supply through a needle valve. As air flows through the carburetor, it passes the venturi, creating a low-pressure region that draws fuel from the bowl through the jets into the airstream. The float rises with the fuel level and pushes the needle valve shut to keep the bowl at the proper level; when the engine needs less fuel, the float falls and the needle valve opens to admit more fuel. In short, fuel metering is driven by air intake through the venturi, with the float mechanism maintaining a steady fuel level in the bowl to regulate how much fuel is available to be drawn into the airflow. This is a mechanical system, not electronic sensors or hydraulic pumps, and it responds to air flow rather than throttle position alone.