What is the function of an accelerator pump in carbureted systems?

• A. To reduce fuel pressure at idle.
• B. To provide a quick, temporary enrichment during rapid throttle opening and prevent hesitation.
• C. To monitor air mass entering the engine.
• D. To regulate exhaust gas recirculation.

Answer: (B)

The accelerator pump injects a short burst of extra fuel when the throttle is opened quickly. This immediate enrichment keeps the air–fuel mixture from going too lean as a surge of air rushes into the engine, preventing hesitation or stumble during rapid throttle movement. The pump is driven by the throttle linkage, delivering fuel through a discharge jet into the intake to match the sudden air increase until the carburetor’s main metering can take over. It’s not about lowering fuel pressure at idle, monitoring air mass, or regulating exhaust gas recirculation—that’s why the pump’s job is specifically to provide that temporary rich enrichment for smooth throttle response.