I have a 1983 Mustang 5.0 HO that had a carb leak a month ago that was repaired. Even since the repair, it has a gas smell that is detectable after driving the car. I cannot smell gas while driving, but after the car sits in the garage overnight, the next morning it reeks of gas. 3 different mechanics since have looked at it, tracing the fuel line from carb to tank, they found nothing. No sign of leaks. Carb looks good. Someone said to replace the gas cap, which I did. The smell remains. It is not noticeable while driving. (Also, the car requires 5 or more pumps of the accelerator and 3 to 5 turn overs to get it to crank when cold. Once warmed up, it cranks easily the first time.) I have no idea what it could be.