This is a clear sign of a problem in the EVAP system, specifically the charcoal canister.
Your gas tank needs to breath in, to allow air to displace the gas pumped out and when the gas contracts during cooling, and out, because the volume in the tank inceases (1) whenn you fill it, (2) when the gas warms up in the sun, and (3) when the fuel is agitated as you drive (agitated fluid takes up more volume). In order to allow it to breath while still preventing hydrocarbon molecules from getting into the atmosphere, it breaths ina and out through an activated charcoal bed. The component that contains this is called the "carcoal canister". The charcoal catches hydrocarbon molecules in air that's escaping the tank, and when you start the car a solenoid-operated "purge valve" and allows the HC to be drawn into the engine's intake system and burned.
If the vent line to the canister becomes blocked or kinked, or if the charcoal bed becomes saturated with gas, the tank will be unable to breath in. A vaciuum will form in the airspace and the vacuume will prevent the pump from being able to pump gas out. It also places excess stress on the pump and can cause premature pump failure.
I've attached an "exploded view" drawing of my owne system just to illustrate the typical system. I don;t heva one specifically for your system, but I'm coonfident that it'll be similarly constructed.