Which of the following is not a problem associated with pressure-type carburetors?

Vaporization icing is not a problem typically associated with pressure-type carburetors. Pressure-type carburetors are designed to maintain a consistent fuel flow and atomization regardless of altitude and temperature changes. These carburetors operate under pressure, which helps to ensure proper fuel delivery to the engine, minimizing issues related to icing from fuel vaporization.

In contrast, vaporization icing is more commonly a concern for float-type carburetors, where fuel can cool down and potentially freeze or form ice in certain conditions due to the drop in pressure and temperature as the fuel is vaporized. The pressure-type design effectively reduces the likelihood of vaporization icing occurring, thus making it less relevant to their operation.

Other problems mentioned, such as fuel leakage, fuel evaporation, and air entrapment, are more likely to be issues in pressure-type carburetors due to their construction and the way they handle fuel under pressure, which can lead to different challenges compared to vacuum-operated systems.