if youve been running all this time with the setup it works. normal maintenance like tubing changes should solve issues . $300 worth of tanks lol [im guessing by size and odd shape] isnt magic solve it all. dozens of records have been set with plastic tanks.
it seemed you said the engine had 20 "starts". a few things --
-are these just test starts ? i.e new engine or new bearings
-is the engine had more than 1 owner?
--was it running normal/full speed/finishing all laps before
in any case ive seen a guy with twins put in new bearings and have same issue for a whole weekend. went thru all the stuff stated here (only with metal tanks) and still nothing . it would do 2 really good laps like its almost running perfect then both engines shut down . look like could be radio right ? changed that too . evenn changed the throttle servo .
next week he changed bearings and the boat ran again . why? who knows. maybe damaged on install ,maybe bad bearings,,but both ? 2 engines ? i never understood it. ive also seen it happen with a single 45 .
it seems the draining the tanks with pump till empty test works for me as long as a) no bubbles randomly and b) u have to test the pressure line separately some way,,usually just replace it
but if the engine warms up then dies OR if u look at it properly its leaning out slightly because of less fuel pressure cause the tanks are 2 3rds done their laps then its a tiny leak that ur compensating for with a richer setting on stand .
a fuel system leak -seams ruled out to me . or bearing leak which will show when warm up enough. it gets worse and shows when the time till shutdown gets shorter and shorter,and/or youre richening more and more to get same run time .
cantilever style engines are a pita in boats imo.
in any case (long post) u can also check head button,,stupid but ive seen a couple cmb cantilevers that had the headbutton start leaking after a few laps . idk why/how. possible inconsistency in manufacturing
