Hi,We have just purchased a 2002 Beneteau 50 fitted with a Volvo diesel and twin fuel tanks in each of the stern cabins.We cannot figure out how the fuel supply is switched between the tanks, as one is showing nearly full and the other only 1/4 full. The Beneteau boat manual only shows a fuel cut off valve on the port tank and no other valves.Any suggestions would be appreciated.ThanksTony