I replaced the tank and sending unit on my 69 last fall. Everything was working perfect all summer. Today I went for a cruise and the fuel guage was not working right. Should have been a half tank of gas. On accelleration it would drop to 1/4 tank and when I slowed down it would go back up to half. Periodically it would go to full (which I believe means no powerf to unit or guage) and then in a minute or so back to proper reading. Any thoughts on what I am experiencing? Thanks...Jon

Periodically it would go to full (which I believe means no powerf to unit or guage) and then in a minute or so back to proper reading. Any thoughts on what I am experiencing? Thanks...Jon

Usually means sender wire is intermittently open. When the sender wire is open, a fuel gauge will peg to "F". First check the ground connection at tank, make sure its bolted to clean bare metal and use a star washer(this helps make a good connection).