’66 Newport fuel gauge not working

I stopped to put gas in my Newport the other day. When I left the gauge read a half tank (which is accurate since I can make fuel last a while considering it's my weekend only driver). About 15-20 minutes later I happened to look down at the dash and saw the gauge was on "E". I didn't lose any fuel anywhere so I know I have fuel in it. I'm wondering if a fuse blew and, if so, which one is it? Or did something else go out in the tank??? Any ideas?
Author: 5fty7vn