I have a 17.5ft crestliner fish hawk pro(fishing) boat, with a 40 gallon built in tank. The boat is a 1998, the tank has a sending unit on it and an old fuel gauge from the previous johnson motor. I just got the 2003 f115 4 stroke with the new digital gauges. How do I wire the fuel sending unit directly to the new digital Yamaha gauge? Is there some kind of adapter?