Jeff,
The only thing I can add to this discussion is that I once had a pick-up tube inside my tank that had a corrosion perforation a couple of inches from its bottom end. When the fuel dropped to that level the pump sucked air. Not likely to be your problem if you have recently driven the car till the tank was near empty, and certainly not with the work you had done to the tank, but when all else fails . . . . . . Blowing through the line should tell you -- no bubbles, just air, while there is still fuel in the tank would mean pick-up tube failure of some sort.
Good luck,
Bob S.