i had this problem a few years back on a 92 940 sedan i bought to fix and sell. the first time i filled it up at the gas station all of sudden gas is pouring all over the ground out the back end under the tank.

upon close inspection it was not the tank at all. it was the gasket and bung nut which seals the top of the tank and holds in place all the fuel lines, tubes and sender unit with pump attached.

the gasket seal was bad the bung loosened so everytime you filled up the gas just poured out the top rather than run up the filler tube where pressure changes would shut off the gas pump handle.

look there at the bung first. there is an access panel in the trunk of a sedan or in back cargo area for a wagon.