Help. What could it be?!

Hey there,

Long time user of the forum, finally time I’m here with my own problem to be solved. Thank you all in advance for your help, and for the years and years of learning about my machine you all have provided.

Ok, so. Here is the break down: boat is a 1991 ski Nautique 351w. Brand new engine as of 5 hours. New SKIDIM protect conversion kit, new fuel pump, new battery, new starter.

The second time out with the boat with the new distributor in, the boat ran better than it ever has, was beaming from ear to ear, even at break in RPMs. Anyway I’m about 6 miles from my cabin, the wind picks up, I head back home with family. The engine begins to get very sluggish, I keep on the throttle as I’m thinking it’s a distributor issue, as I had been tweaking it to get it dialed - I assumed it was that. So kept going, by the time I’m at the dock, the engine is seriously sputtering, and had died a few times with a VERY hard start.

I open it up, start it up, and see it’s been flooding out of the J tube massively. I pulled the plugs let it air out. During this time I’m also finding it really has a hard time starting. Obviously.

Week later, new carb rebuild. I turn the engine but it won’t turn over “well” feels like a lot of pressure, or that the battery is dead, and indeed the battery is being pulled very hard and the ground wire at the battery is very hot.. I then go ahead and buy a new starter, as I assume that the solenoid is working as it’s giving power to the starter.. new starter in, but now cranks the engine over a few times ( with a new fully charged battery only) but engine wont start up as it only gets a few revolutions before it feels like the battery is dead, it pulls from 12V down to 10 very quickly on the gage.   So, I check the power coming from the relay to the starter ( it’s a one wire configuration) and when I turn the key, the starter is only getting 6.5V max.. the other thing that is happening is that the relay output is showing 12.3V from the output ( to starter) when checking the volt reader touching the engine as ground….   So.. with all this back story. And being that I’m on a northen BC lake and all parts from the USA take weeks and cost a lot to ship - what do my symptoms tell a trained ear/eye?    

Another important note is the the engine cranks over fine with no spark plugs, manually it cranks fine, and same with running the starter, when plugs are in, it manually cranks with some force, I’d say 60lbs of force or so.    

Anyways, log back story, but I’m really hoping I did not destroy my new engine. Anything I should test? Could it be the solenoid “welded” as I’ve heard can happen.

Thanks again.

Thanks so much for the reply. I am going to check again to see what the relay is getting while I’m cranking it over. I think it’s odd that it’s only getting 6v to the starter, that’s not good right? Here is a video so you can see/hear what’s going on.   The timing is pretty well to spec, but i will go ahead and pull the plugs and re-set up the distributor, i had no idea it could cause high battery draw. Here is the video. Let me know what you thing https://youtube.com/shorts/zsmdVs_9w1I?si=iumCVlzuEX4UWvYH

Keep in mind a DC motor is a dead short at 0rpm

Great idea (s) thanks for the help here! I have ordered a new Solonoid/relay this week and new key / switch ignition. Once I am back to the boat, I plan to install that.

The battery/batteries are both new, marine batteries that i have been using to test. Both worked well when the boat was running well. I don’t have the specs on hand but can add them

Great idea on running another battery cable, and ground. Any idea what gage the wire is and length by any chance ( happy to cut longer ) I will build two new wires this week to go test.

That’s interesting. What exact battery should I be running? So much almost too much information. Willing to buy a new one this weekend.

Update here. Just put a new Solonoid from SKIDIM and nothing. Sounded like it almost wanted to go. The killed the battery as usual, I’m only getting 5V at the starter.

I have all new solid core battery wiring and terminals. So that’s the next step.

Very interested in the correct battery selection.

Yes. This is the battery https://www.canadiantire.ca/en/pdp/motomaster-nautilus-group-size-24-starting-battery-675-mca-0102493p.0102493.html

So great question. It’s getting 12.6 to relay when ignition is on. Just now I tested and the engine is trying to start, but as it’s cranking over and over the volts are dropping, they dropped in a few seconds to 9, then a few more revolutions and down to 5.5-6. It’s now sitting 12.4 with the ignition on, and only cranks to 6 when I just tried for the second time.

Engine pulling too much of of the battery? Or ground? I’m about to install new 1/0 awg solid cables

Thanks for all the help. I installed a new ground wire(s) and ignition switch. And seem the engine is doing the same thing.

Keno -I’m starting to think that you may be correct in thinking that it’s just drawing too hard, which makes me think it’s likely that I did some sort of damage to this brand new engine when it flooded. Two starters doing the same thing, two relays, and it all happened after the flooding.

Guess it’s going back to the engine shop.