Gas gauge woes..

I will check all these things tomorrow. I got company today and could not go in the garage. I will say I never knew there was a body ground????? Are there two grounds?
I only know about the ground that goes from the sender to the fuel line. Are there two grounds?
The original line was left on. I cut some of it off when I replaced the gas tank. It was pressing against the new line. I am starting to wonder if that old line I cut off was grounding the new one since it was pushing against it.