Hello,

I have a 1996 gen VI 502 mag mpi in a 97 fountain. It has started cutting out above 4,000 rpm intermittently.
Gauges aren’t doing anything weird, besides the tach falling a few hundred rpm. I did do new ignition system parts about 30 hours ago. New plug wires, coil, pick up coil, module, jumper harness cap rotor.
This season I had the injectors tested and cleaned, replaced the rubber line from the tank pick up to the fuel shut off valve and from there to the filter head. New ac delco mr43t plugs put in maybe 10 hours ago. The previous owner of the boat had the heads, gone through, new cam, emi exhaust, ecu was tuned by Arizona speed and marine and a new cool fuel pump and adjustable fuel pressure regulator down under the block by the fuel pump where all put on about 100 hours ago. I’m planning on putting another new fuel filter on, pulled spark plugs tonight and all of them look pretty white/lean(picture attached) leading me to believe this maybe be a fuel delivery issue? Filter or fuel pump possibly?
I did do the grab and wiggle and shake test with the boat running on the wiring harness etc around the engine, kill switch and ignition switch at the helm Looking for any insight or something I am over looking.

thanks

Start with the basics. Plugs, wires, cap and rotor. Do a compression test and check the fuel pressure. You will find 95% of the issues by doing this.

yea, I did cap rotor wires etc about 25-30 with all of boats unlimited parts. I did do a compression test just 10 hours ago when I did plugs, all within a few pounds of each other and 160psi. I have not check fuel psi yet.

what is the spec on the fuel pressure?

im also going to grab a friends scanner and see if there are any codes that pop up.

I should also add what I forgot. The boat did do this in early July, at which I did do the new plugs, comp test and new fuel filter which cured the issue then. Kind of leaning to fuel issue with the color of the plugs, and if the new fuel filter clears it up I’m wondering the cool fuel screens are plugged or weak mechanical pump

Fuel pressure 43 psi

what coil did you install

oem coil, was part of BUP’s ignition kit

Let me guess he did the injectors also ?

correct

Describe “cutting out” in a clear/concise way so we may better understand what could be happening.

When it starts getting above 4,000 it’s almost like you were to hit the ignition or kill switch for a split second. The tach will fall back 2-300 rpm. Sometimes it not as pronounced, but you can feel the boat pulling back, as if you were almost hitting weed patches or something.