FAA Powerplant Written Practice Test

What does the accelerator system of a carburetor primarily do?

1. Reduces idle speed

2. Increases fuel flow during rapid throttle movements

3. Stabilizes fuel flow

4. Regulates air intake

The correct answer is: Increases fuel flow during rapid throttle movements

The accelerator system of a carburetor plays a vital role in managing fuel delivery, primarily during instances of rapid throttle movements. When there is a sudden increase in throttle position, the engine requires an immediate and proportional increase in fuel to maintain optimal performance and prevent hesitation. The accelerator pump within the system injects an extra amount of fuel directly into the induction system, compensating for the lag that occurs with normal fuel delivery systems. This boost prevents the engine from experiencing a momentary lean condition, allowing for a smooth and efficient acceleration response. In contrast, other options present different functions. For instance, reducing idle speed pertains to different mechanisms focused on engine management at low RPMs, while stabilizing fuel flow is more aligned with maintaining consistent operation rather than addressing rapid changes in throttle. Regulating air intake connects to the engine's air-fuel mixture balance but does not specifically target the immediate demand for additional fuel during acceleration. Thus, the primary function of the accelerator system in this context remains centered on enhancing fuel flow during those swift throttle inputs.