Final answer:
The single diaphragm accelerator pump in a carburetor discharges fuel when the throttle is opened quickly to provide an instant fuel boost during acceleration.
Step-by-step explanation:
The single diaphragm accelerator pump in a carburetor discharges fuel when the throttle is opened quickly to provide an instant fuel boost to prevent hesitation or stumbling during acceleration.
When the throttle is opened, the vacuum created by the engine draws fuel from the float bowl into the pump well, causing the diaphragm to move downward.
As the diaphragm moves down, it pressurizes the fuel and forces it out through the discharge nozzle into the main metering circuit of the carburetor.