Ok, thanks for all the input "BUT" I must have some other problem here goes!
I don't have fuel gauges just a really nice stick. I filled both tanks to with-in about 2" of full. My fuel system only returns to one tank (starboard), it also has an electric fuel pump. I was concerned that because it only returned to one tank that a should use some fuel from that tank first.
After running about 7 hours the boat was listing to the port side I measured the tanks with my custom stick and port tank was still about 2" down as is was turned off the starboard tank was down about 5".
So I switched to both tanks ran about 7 more hours when I stopped fuel was coming out of the over flow on the starboard tank!
Using the custom stick I re-measured the tanks, port down about 5" starboard full to the top!
Any ideas would be great!
Sorry for the long post