I agree. The car is 23 years old and the carb has been touched only once, Ford issued a recall for a "fix" in 1986, never obtained good gas milage after they "fixed" whatever it was (dropped from 28 mpg on the interstate to 21 mpg).
But a sinking float or bad needle/seat doesn't explain the pressure in the tank after the key is turned off.
Did find a fracture in the hose connected to the intake of the fuel pump last night, may be the source of the fumes.
I'll be pulling the carb for inspection this evening. | 
