Check cockpit deck pie plates. They leak
Check one over gas tank pickup and look for wet foam, wetness, bad wood, gas odor, wires to fuel sender...
gas tank can fail do leaky deck plates
Some say a gas tank pressure check is good, others do not
Check cockpit deck for softness and jump around the cockpit to check the deck is tight
Open all windows and check them and frames for corrosion
What year is the motor? some Yamaha 4 strokes have issue called dry exhaust corrosion and expensive to repair
Scan the OB with computer with YDS software and look for codes and hours at various rpms. A full report can be printed
Inspect wiring around batteries and helm for add ons, poor wiring or tinkering
When were batteries replaced?
Does it have a RACOR fuel and water filter?
Others will reply
Good Luck
