Which of the following is NOT a common cause of engine flooding?

Low fuel levels are not a common cause of engine flooding. Engine flooding occurs when there is an excess amount of fuel in the combustion chamber, which can happen due to issues such as excessive fuel injection or poor ignition that prevents the fuel from burning efficiently. When fuel is being injected excessively, or when the ignition system is malfunctioning, it can lead to an accumulation of unburned fuel, causing the engine to flood.

On the other hand, low fuel levels indicate that there isn't enough fuel available for the engine to function properly, which would more likely lead to stalling or insufficient power rather than flooding. Therefore, since flooding is primarily caused by an overload of fuel or problems in the ignition system, low fuel levels do not contribute to engine flooding.