Stereo & Electronics - fuel level guage only reads 1/4 over full??? Any ideas why?

My factory gauge now only reads "extra full" - like it has lost the ground. The problem, I pulled the harness plugs by the tank and checked the connections, ground is good.

Could it be the ground for the gauges? Only the fuel is reading incorrect. If so, what is an easy way to check it?

Anything else I should do?

Check the "pwr accy" fuse... it tends to do funny things with the gauges.

maybe its something related to this post?

http://www.ls1tech.com/forums/showthread.php?t=186210&highlight=sulfur