Gas leak under car somewhere.

I had the same problem on my 91. There is a rubber hose that runs from the filler neck to the tank and is for fuel overflow that redirects the fuel back into the tank. This hose gets dry rotted and splits. You must get under the car to replace the hose and it's not easy. The hose clamps are tough to get to but DO NOT use coolant line type hose to replace it. These are not designed for fuel applications. An auto parts store should carry what you need. Another problem could be the rubber fuel lines or the plastic connector fittings on the fuel filter or the ones that connect the fuel lines to the fuel sending unit in the tank.