To do it right you'll have to remove the tank, not as big a deal as it
sounds. Many radiator shops repair leaking gas tanks. Our tank had a lot
of small holes on TOP, where it meets the trunk floor where you could not
see them. For that repair the radiator shop cleaned the take out and used a
liquid sealer that is poured in and sloshed around, then dried. It
basically is a tank liner in a can. It works great!
Good Luck
Bill & Tami Roddick
1964 Imperial Crown 4DR HT
1972 'Cuda 340
1988 Cherokee Laredo
1995 Concorde
1997 Wrangler