What causes a car to suddenly stall after prolonged idling?

[OReid]

Reasons for a car suddenly stalling after prolonged idling are as follows: 1. Idle stall: After the engine starts, it runs well from low to high speeds, but stalls immediately when the accelerator pedal is released; or it first runs unsteadily and then stalls. This phenomenon can be identified as an idle stall fault. 2. Unstable idle: When the engine idles, it runs unsteadily, and the exhaust pipe makes a "gurgling" sound, which is generally an unstable idle. Stabilize the engine at a certain speed and listen for any air leaks. If it is difficult to locate the air leak, apply a small amount of oil to the middle and lower gasket areas of the carburetor. The place where the oil is sucked in is the air leak, which can be fixed by tightening screws or adjusting the gasket. 3. High idle: When the engine idles, the speed is higher than the normal range and cannot be reduced by adjustment, which is a high idle fault. When the engine idle is too high, park the car on a flat surface and push the choke knob and hand accelerator knob all the way in for inspection.