You can not fly with only one fuel tank as there's no way to keep the fuel in the required lateral balance.

The airplane has three tanks, left main, right main, and center. You can fly without the center tank. IAD-CLE wouldn't require any fuel in the center tank, though.

What may have happened is one of the two boost pumps being inoperative in one of the tanks. Each tank has two boost pumps. One can be inoperative if the other three are working and extra, unusable, fuel is carried to ensure that required fuel can be suction-fed in the event of a go-around with the second pump failed.