boat hesitating...

This has been an ongoing issue for me since last year. It doesn't keep us from riding, but it is super annoying and I assume can be fixed if we can figure out the problem.

The problem is that it seems to be completely random and intermittent. Basically I'll be driving and the boat will slow about 1/2 mph or so then pick back up. You can hear it "bah, bah, bah, bah" just a little while it does it. Sometimes we'll ride for weeks and no problem and sometimes it happens everytime we are out.

Last year when we had the issue I posted on here did what was suggested: fuel injector cleaner, isoheet, new fuel filter. I've had it at 2 different shops, including the dealer, and neither could find anything. And I know if I pay to have them come with me on my boat so they can experience it, it just won't happen because it is intermittent.

The only guess I have to pinpoint when it seems to happen more often is when I have the boat full of lots of people or when I take on lots of water (like yesterday I was in neutral picking up a surfer and another boat turned into me and sent huge rollers over the back of my boat) Immediately after that roller, I noticed the hesitation.

It seems like it could be a fuel/water issue, but I had this same problem intermittently all last year too, but when I checked for water in the fuel there was none evident.

any ideas?

Always good to know what eng you have to help with these issues. I assume by your profile pic you have and Indmar 5.7L MPI? How many hrs? Have you ever changed the spark plugs? It sounds like you are dropping a cyl sometimes. When its this random its rarely fuel. I would check the spark plugs any build up of rust can make the spark jump out of the boot and not fire that cyl. So check the plugs and spark plug wire connections at plugs. Also if you have never replaced the dist cap. this is a good place to look.Remove the cap look at the little terminals in there if they are covered with a white crusty corrosion replace it.
spark plugs.cap and rotor would be were I would start pretty cheap and should be done every year according to Indmar.

I'm having similar issues and I believe the problem is with the fuel injectors. I'm going to have my injectors reconditioned and then they'll be good as new. I might suggest you do the same. My boat is a 2005 and have over 600 hours. it probably is time to have them reconditioned.

03 Supra Launch SSV with the 5.7 MPI, 325HP I beilieve. Only 246 hours...

Not sure if that engine still has a distributor, but do a full tune up. Cap, rotor, plugs, wires, set timing, etc. Good first step. I'd also get a gauge on the fuel rail and confirm psi is in spec.