Replaced gas tank, won't start!

It's not the carb, I'm sure of that. And actually it probably ran a minute or two before it quit. Everything was fine until I replaced the tank today. After it stopped running when I pulled the fuel line off the sending unit there was no gas in the hose. I'm pretty certain it's between the sending unit and the fuel pump.

The fuel pump wasn't an issue before, it was also replaced last fall. It's an Auto Zone special. I'll put the old sending unit back in it tomorrow, at least I know that one worked. Even the fuel gauge worked.