AG Mechanics CDE Practice Exam

What is the purpose of the venturi on a carburetor?

1. Decrease air speed/increase pressure

2. Increase air speed/decrease pressure

3. Maintain a constant fuel level

4. Regulate fuel intake

The correct answer is: Increase air speed/decrease pressure

The purpose of the venturi on a carburetor is to increase air speed and decrease pressure. As air passes through the narrowing of the venturi, its speed increases, leading to a drop in pressure according to Bernoulli's principle. This drop in pressure helps to draw fuel into the airflow for proper fuel atomization and mixing before entering the engine's combustion chamber. This efficient mixing of air and fuel is essential for engine performance and combustion. The other options are incorrect: - Decreasing air speed and increasing pressure (Option A) would go against the principle of how a venturi works in a carburetor. - Maintaining a constant fuel level (Option C) is not the primary function of the venturi but rather the job of the float and fuel inlet valve in the carburetor. - Regulating fuel intake (Option D) is a function of the entire carburetor system, not specifically the venturi.