the main fuel line in the tank has a leak so if you let the gas drop under the gas line it gets air in line

You should mention what year/model car you are needing a tank for. They are not all the same. If it is just a leak I am sure you could remove the tank and get it repaired.

-Mike

You might want to check out www.zpartswarehouse.com. I just bought a few items from them. They have a massive supply of 240z - 28zx parts. So far they have had everything part I have asked for.

Buddy, that happened to my '75 long ago. It's pretty baffling to run out of gas when the tank is half full!

You don't need a new tank, though. Just take your tank to a good radiator shop. They'll be able to repair it fairly economically.