http://tijil.org/Scion_Docs/Scion_06_misc_docs/2007sciontc_ncf%20Folder/2azfeemi.pdf
I’ve attached a sketch of a typical vapor recovery system. When gas is pumped in, the rising fuel in the tank raises pressure beneath the diaphragm of the Refueling Valve, the valve opens, and the tank is able to breath out through the charcoal canister. If the refueling valve (which includes the restrictor orafice), the charcoal canister or the evap valve are malfunctioning, the tank will be unable to breath out.
Two things to note: (1) this system is not yours epceifically, but they all operate similarly, and (2) on some older vehicles, “topping off” can allow the charcoal canister to get saturrated, and if that happens the tank will not be able to breath out and refilling problems such as yours can develop.
I cannot diagnose your car from here, but this’ll give you an idea of what’s wrong.