What happens if the idling jet becomes clogged in a float-type carburetor?

If the idling jet becomes clogged in a float-type carburetor, the engine will not receive the proper fuel-air mixture necessary for smooth operation at low speeds. The idling jet is specifically designed to supply fuel when the engine is at idle or low throttle settings; when it’s clogged, fuel flow is restricted, leading to insufficient fuel mixture. As a result, the engine cannot maintain a stable idle, which often manifests as stalling or rough running.

In this case, while the engine may attempt to run, it will fail to keep idle effectively. It's important to note that if the idling jet is obstructed, the engine may struggle, sputter, or even stall due to a lack of fuel despite the throttle not being fully opened. Therefore, the inability to maintain an idle directly ties to the function of the idling jet, making this the correct answer.