In a carburetor, air flowing through the air horn and venturi creates a difference in what property between the fuel entry ports and the float bowl?

• A. Pressure
• B. Humidity
• C. Temperature
• D. Density

Answer: (A)

When air speeds up through the air horn and venturi, the static pressure drops in that region (Bernoulli/venturi effect). The float bowl is open to atmospheric pressure, so a pressure difference arises between the venturi area and the fuel in the float bowl. This pressure drop pulls fuel up through the jets into the airstream, creating the fuel–air mix. Humidity, temperature, or density aren’t the primary drivers here—the key factor is the pressure difference.