fuel issue after car sits.

ive had this happen a few times one time was the rubber fuel line from tank was old and rotted one time it was the new hose that instaled the hose clamp put holes in the line from tighting to tight what i allways did to figure it out was to park the car in a dry place and put (clean) card bored under the car from front to back on the passenger side were line is and it leaked down over night and wala there it was cant miss it