It's more likely that since the car has sat for a while that the fuel tank outlet is partilally plugged. I used a piece of #12 copper wire to clean out the supply and return tubes. If you remove the drain, you will also find a strainer which could be plugged.

You might also try putting a quart of carb cleaner in the tank, let it sit overnight, and then drain it in conjunction with cleaning the lines with the wire.

Good luck

Chuck