I have a new to me (3 years) 1999 272 Sailfish with twin Yamaha 225 OX66 engines. There are two fuel tanks - a 150 and 50 gallon. When I bought the boat both tanks had water in them so I had them emptied and cleaned of varnish. Also, I had the fuel system replumbed to eliminate the 50 gl tank since I don’t need that high capacity of fuel. So only the 150 gl tank is being used now. I ran out of gas. The fuel gauge showed 1/3 full. The fuel monitor, which is very accurate, showed just over 100 gls used. Can’t tell if the tank is original, but I suspect it is. The fuel pick up tubes are welded into the tank so I can’t tell how long they are. The entire fuel system has Checked out OK. Essentially I can only use 100 gls out of a 150 gallon tank. This can’t be right - what am I missing?