Can't get gas into the tank, acts like it is full, but it is empty

Have you crawled underneath to look at the tank? I have had the tank implode due to a clogged vent tube. This happens when you have low fuel level on a hot day, and it gets cold overnight. The tank is full of gas fumes in the daytime, which condense as they get cold, causing a vacuum. This can pull the tank flat. In the morning, I was surprised to see the gauge read 3/4 full instead of almost empty. I figured it was the gauge, and went to fill up. I could only fit about 1-1/2 gallons. So I looked underneath and saw a crumpled tank. BTW, this happened in the fall at high altitude in the Sierra (95 in the daytime, dropping to 40s at night). It's unlikely to happen in your driveway, but...