I bought a used car from chicago suburb individual owner about 15 days ago. clean title with no accident history. the gas tank during last 15 days was never little above half tank. today i filled gas full tank and drove about 8 miles and parked in home garage. liquid fuel leak from rear side of the tank was observed forming a puddle in garage giving strong gas smell in few minutes. when i looked under the car, i could continuous drop by drop liquid fuel leak. i confirm that i did not observe any leak in last two weeks when gas tank was less than 3/4 or less full.in last 15 days i consider lucky that the leak did not take place over exhaust gas pipe while i was driving. i have towed my car to a repair center and will advise him to save evidence.