They are solid engines and reliable, parts and finding mechanics who are experts at trouble shooting them are not. I replaced mine with a remanufactured long block last year. I still am chasing ghosts as the computer will not let me take it over 3500 rpm. Even ford racing who designed the efi set up cannot offer me help.
Had a 75 MasterCraft ski boat with a Ford 351W in it. It was a reverse turn inboard. It was a great motor and lasted many hours. Rebuilt it just before I sold it and it still ran very good. No computers back then. Found out later that it had a leaking exhaust manifold that I missed, but was an easy fix. It was pretty much bulletproof if you took care of it.
As far as fuel goes, it wasn't all that bad in an 18 ft. boat, but then fuel was a bit cheaper back then.
Boat motors are only as thirsty as your right hand moves forward. I can burn up the 40 gallon tank in a day if I tried or go the same distance and use half at a nice cruise speed.
