FAA Powerplant Written Practice Test

Which part of the carburetor helps control the fuel flow specifically during acceleration?

1. Venturi

2. Throttle valve

3. Accelerator pump

4. Float assembly

The correct answer is: Accelerator pump

The accelerator pump is a crucial component of the carburetor that specifically addresses the need for additional fuel during acceleration. When the throttle is opened quickly, the engine demands an immediate increase in fuel to match the increased air intake, ensuring that the air-fuel mixture remains optimal for combustion. The accelerator pump provides this extra fuel by delivering a shot of fuel directly into the venturi, enhancing the mixture and preventing potential hesitation or stumbling during acceleration. The other components play different roles in the carburetor's functionality. The venturi is primarily responsible for creating a low-pressure area that draws fuel into the airstream but does not actively control fuel flow during acceleration. The throttle valve controls the overall amount of air entering the engine but does not provide the instant fuel enrichment required during quick throttle application. The float assembly regulates the fuel level in the float chamber but does not interact directly with fuel flow during acceleration. Thus, the accelerator pump is uniquely positioned to assist during these critical moments in engine performance.