Originally Posted by
korey
I had issues like this on my Nautique 2001 (same engine setup). It turned out to be that the mechanical advance on the distributor was sticking and never fully advancing. it wouldn't make any power in the top end. You could use a timing light to make sure that it advances at higher RPM. I don't believe that you should have vacuum advance, so load won't matter (unless I'm wrong about vacuum advance - is there a vacuum line running to the distributor?). I ended up replacing the distributor to fix this, but you could probably disassemble and clean it. If i recall correctly, mine was more worn out than dirty. That boat had like 2500 hours on it.
Also, run the boat without the engine cover (if possible) and see if the secondaries are in fact opening at WOT. For this you will have to be under normal load - so running down the lake.
THIS. Distirbutor mechanical advance sticking or vacuum secondaries on the carb not opening. Also, check to make sure all plug wires are seated on the plugs and distributor cap are seated fully. You'd be surprised how well one of these motors will run on 7 cylinders. Only symptom is a slightly rough idle and loss of power at speed. Ran half a season years ago before I figured that one out.
1992 Supra Mariah - Red
PCM 351HO 285hp - PCM 1.23:1 Transmission
OJ XMP 4 Blade CNC 13x15.5RH
"People do weird things to boats" -Unknown