Fuel odor

[just-n-time]

Hi just-n-time here, I have had a gas odor in the trunk, I have spent a good deal of time under the car trying to find wet lines but no luck,today I replaced the fuel cap and my wife said as soon as I did that the smell stopped, So I thought maybe it is the o-ring under the fuel sending unit, I replaced it too. I found no obvious damage to the o-ring.Has any one else had this kind of trouble?1990 420sel