Are these closed cooling systems?

Check the antifreeze and make sure its not full strength the motor will run hot and detonate. I have seen this many times before in cars and heavy equipment. Had a ford would drive it down the road and it would sound like marbles came back to the yard dropped a gallon out and put water in and problem was gone.

reported 431 deg f lake water temp.i think that sensor might be faulty!what is this BUP?

jeez Mike I was going to ask that same question. No actually its relates to the paddle wheel in which serves 2 purposes if you have one. In which in his case I would say 99 % he does not. The paddle wheel spins for MPH reading and has a sea water temp sensor built into it so it can read water temps as well. Without the paddle wheel connected / linked to smartcraft and in his case he does not have one - the temp reading will default to what the highest listing was. Temp 431.60. If you notice both engine scans read the same exact 431.60 (default number) for the basic jist of this.

There you go for todays lesson. LOL

good info as usual.

What is the fuel pressure at full load?

unfortunately I don't have that number right now hallj, this is probably going to take several weeks as I have to break in a couple motors before I'll be able to run WOT to verify pressure side. I love the idea of a vacuum gauge on the source side and the clear tube for visual verification (you can see the inline filters mounted to the bulkhead at the front of the engine well). Couple pictures below of the fun

well you dove right onto this project!looks like you will be boating in no time flat.

Fired the motors today, they sounded good but have a sensor issue with the one...will most likely start a new thread

What boat is it?

2003, Warlock 31' SXT Cat