Which statement is true about the Venturi in a carburetor?

• A. It proportions air-fuel mixture
• B. It increases fuel temperature
• C. It blocks air flow at idle
• D. It filters fuel

Answer: (A)

The Venturi’s job is to create a predictable relationship between the amount of air flowing through the carburetor and the amount of fuel drawn into that air stream. As air speeds up through the narrow throat, its pressure drops. That drop in pressure sucks fuel from the fuel metering system into the airstream through a jet, and the amount drawn in rises with the air flow. In this way, the Venturi helps proportion the air and fuel to maintain a usable mixture across different engine demands.

It doesn’t heat the fuel, it doesn’t act as a filter, and while idle circuits exist, the primary purpose of the Venturi isn’t to block air flow at idle.