Replacing gas tank in my '65 Dart...

I had the same problem with my 67 fish car. The gas was bad, the tank was rotten and rusty and the pickup sock was nowhere to be found. The bad "gas" in the tank got sucked up into the pump and clogged it as well. I would recommend you replace everything since tanks are cheap these days. Get a new pickup screen too and take your pump off and either replace it or shake the old crap out of it. Don't forget to also replace the filler gasket because your old one is brittle and won't seal.