How does a carburetor introduce fuel into the air stream?

The introduction of fuel into the air stream by a carburetor is primarily achieved through the venturi effect. As air flows through the venturi, which is a narrowing in the carburetor's passage, the velocity of the air increases while its pressure decreases. This drop in pressure creates a vacuum that draws fuel from a small fuel jet or nozzle, located at the venturi. The fuel is then atomized, meaning it is broken into small droplets, allowing for efficient mixing with the incoming air.

This process ensures that the air-fuel mixture is optimal for combustion in the engine’s cylinders, providing the right balance for efficient operation. Unlike direct injection systems where fuel is injected under pressure, the carburetor relies on airflow dynamics to mix the fuel with air before it reaches the engine.