In low-speed operation, fuel is discharged through a port located just above the throttle plate. What is the name of this circuit?

• A. Transition circuit
• B. Accelerator pump circuit
• C. Cold air induction system
• D. Fuel pressure regulator

Answer: (A)

The situation tests how fuel is metered during throttle movement from idle into the mid-range. As the throttle begins to open in low-speed operation, the engine needs a little more fuel quickly to keep the mixture from leaning out. The transition circuit is designed for exactly this stage, delivering a small amount of fuel through a port located just above the throttle plate into the incoming air stream. This enrichment helps smooth throttle tip-in and prevents hesitation as you move from idle to part-throttle.

The accelerator pump, by contrast, supplies a rapid burst of extra fuel only during quick throttle openings, not the steady, gradual transition described here. The cold air induction system and the fuel pressure regulator serve different roles altogether—cooler intake air for power (not fuel metering during throttle movement) and maintaining consistent fuel pressure, respectively.