35 fountain with twin hp500 clones, Holley 750 cfm double pumper carb, thunder bolt distributor with MSD blaster 2 coil, NGK BR6FS plugs, Hardin marine electric fuel pump.

took boat out the other day for a poker run, started fine and idled fine. Ran about 10 miles pretty hard took a few pretty decent size waves and slammed and sounded like I was missing. Checked everything over and restarted boat and idled for a little but still sounded like it was missing so we putt back to launch.

fast forward to today attempting to diagnose no start problem, boat will crank and sputter a few times and then backfires up through carb. Pulled plugs all showed a rich condition and were wet. Had no spark, so proceeded to change cap and rotor, put a new msd ignition coil in, pulled carb apart and cleaned and sealed. Checked compression all read between 165-175. Checked timing, checked plugs and firing order. Put new plugs and cranked it and still would sputter and back fire through carb.

I’m not sure why i waited til the end to pull fuel filter but I did and it had water and some junk in it when I dumped it so got a new fuel filter and pulled the line thru the fuel pump and let about 3 gallons pump through all gas looked good. Cleaned lines installed new filter and thought this was the moment everything was right. Turned it over and same thing fired a few times then died and backfired through carb.

Last time I cranked it started squealed as though it was stuck now so I’ll have to dive into that tomorrow. Also worth noting pulled a plug and held it to the block to test spark and it was sparking without the key cranking.

Any one have any ideas I’m lost

I'm assuming only one eng is having problems. Sounds like a bad connection or broken wire somewhere. I'd be looking closely at the primary ign wiring. You could pull coil wire from the distributor and insert a spark plug into the coil wire. Lay plug down on top of eng so you can see it while moving the ign wiring around (with ign switch set to RUN).

If nothing found there, swap distributors with the other eng.

Fuel pressure?

I would check the module in side the distributor . that sort of sounds like when they start going bad.

What squeeled ? A belt ? A piston ?

Water and junk inside filter you say ? How does other motor run ? Do they run off same fuel tank ?

Yup.