Limp mode & won't start

Ok grand wizards of the interwebs...:)

As my username suggests...96 SN EFI (GT40).

So I dry-land run tested my thermostat with a hose in idle and it opened and the temperature went back down.
So I launch and as I watch the temperature keep creeping up as I cruise along I'm wondering WTH! It hits some magic point and drops into limp mode. Pretty cool function. I limp the thing along for a little ways until I get to the dock. The temperature stays a little under 200 (maybe 210?)
question 1...does dawdling along in limp mode do any damage?

After everything has cooled down...
I tighten everything down yet some more. I remove the thermostat and there's no water in that larger cavity below it. I fill it. I run it around a little and the temperature barely lifts off if at all. Lake is 72°ish. I open the RWP and the blades are all there. Last year I had a brain fart and somehow managed to thrash the impeller. I put in a new one. All seemed good.
I'm curious to see where the problem might be so I take the rwp line off the thermostat housing and remove the coil wire from the coil under that cowling thing on top and start cranking. It's sparking finding ground on something to the left (facing the front of the engine) so that's good. Some water comes out of the hose so that's good.
question 2...is it correct that water would get pumped out the rwp intake at the thermostat housing seemingly from the circulation pump?

I take the thermostat housing off and lo and behold rubber in that little cross pipe from little to big cavities. Extract that thinking hey there we are. Here we go. Put everything back together (yes the coil wire too) and try to start. Crank. The odd single stumble. No turn over. Crap. Now what!?

Here we are the beginning of summer in my neck of the woods and I have a dead boat. I'm about 4 hours from the nearest Nautique dealer with an almost 20 year old trailer of unknown brake condition seeing as how I'm able to just go for short jaunts to the launch. I don't know if anything's bad with the trailer brakes and I do little to no maintence on them for the reasons given. It's frickin' hot out in the blazing 90° heat.

Anyway...thanks for reading my rant. Please...ideas!?

Thanks

Thank you for the reply.

Great. I look forward to replacing the collection of pipes and hoses. $$$

I disconnected the coil wire so as not to fire the engine for testing the rwp. Just so I can crank and hopefully see water come up from the rwp. Which I did.
The rwp line connects up at the thermostat housing. Then water presumably flows down into the large line going down and around to the circulation pump. When I had the rwp line disconnected at the thermostat housing and cranked...I also observed water coming out that same intake at the thermostat housing with the rwp line disconnected.

I thought I had written details. Sometimes I get accused of providing too much detail! It cranks. There's spark at the coil. It doesn't catch and run.
If you're terrible then perhaps you might not accuse others :) I'm no expert either.

Thanks

Relative to the thermostat. The thermostat should open at 160 or 143(if you have the wrong one). If the thermostat is closed you won't get water to the circulating pump and the lower thermostat housing. It will mostly be pushed out the upper thermostat housing to the risers.

To jhersey29 at 7:24 my time.
Hmm. That's not what I see. I think (I'm not certain) the water comes from the rwp to the thermostat housing into the little front tube of the thermostat housing that then appears to go down and around to the circulating pump.
I then discovered that I had a piece of impeller in the little passage from the front little tube cavity over to the back larger thermostat area cavity.
I do still wonder why I had water coming out that small tube from the circulating pump while cranking.

Thank you for the reply.
Already done immediately after I shredded the last impeller somehow accidentally.

I wonder if I'll have to bite it and open some things up and see where else any other bits of impeller might be. ie. downpipe to circulating pump, circulating pump, output lines to manifolds, manifolds as much as visibly possible, risers as much as visibly possible. I've read here about pieces ending up in the tranny cooler area. How is that possible when the water is supposed to go the other way?

None of this explains why it won't even start though. I'd like it to run so that I can see if I would in fact have to open things up.

Thank you for the reply.

No I've not. I'm not sure how that would be different from what I touched. I had removed the thermostat and went for a short cruise to see what the temperature would do. It appeared to barely move. Maybe it lied to me or it was in fact seeing cold water straight out of the lake.

Indeed, who knows, something else could have coincidentally, unrelated to the overheat decided to give up too.

BTW I also made sure the throttle was up and that the lanyard was in. Maybe those switches have failed, who knows.

With the coil lead disconnected and cranking the engine you would have flooded the engine. The ECM would have kept firing the injectors with a very long (rich) pulsewidth required for starting.

Pull the plugs and check.

You can disconnect the injector wiring loom at back of engine and turn over to clear any excess fuel still remaining in cylinders.

To lewy2001:

Thank you for the reply.

I will try that. I had been wondering what effect cranking might have on things. Is there an easy way to identify exactly which plug of this wiring loom to unplug?

I think the bit about impeller pieces landing in the transmission cooler is left over from the days when cooling hose routing went directly from the hull pickup to the RWP, then looped backed to the tranny cooler before going to the engine.

Either way, it doesn't hurt to check the tranny cooler for debri, as weed and stuff can land in the intake side of it.

So carrying on with the overheat effects...

While idling and marvelling that it's alive I went to look out back at the exhaust. I don't have the swim platform on so I can see immediately out the flapper. Obviously lots of bubbles.
I can't say as I've ever noticed this effect (or lack) before but it seems that on an almost rhythmic basis I could sort of imagine that the engine did an ever so slight "foomp" and then through the water I could see an exhaust or kind of jet of propelled "other" water. Then some moments later "foomp" and exhaust. Kinda like a burp. Is this normal?

I ask because my wife was observing on my dry-land warm-up and saw a burst of water come out. She says maybe about 4 or 5 feet out. I think she reported it when I did a small neutral accelleration. I did not do that this morning. Just idle.
I'm obviously, right now, very wary of anything to do with cooling from the overheat. And still wondering about any other impeller pieces anywhere else from last year.

Thanks everyone.

Wow. Nice job. With boat in the water looking out back with the exhaust water flowing out to lake water yes I suppose it could look like that. So are you saying that's normal? Do you imagine a little bump from the engine as it seems to coincide with those burps?
Thanks

Like I say...I'm just ultra-sensitive right now for anything out of possible ordinary.

I wasn't sure that I wanted to warm up the engine before leaving today and having to put it away hot but I just had to give it a spin. With Bri892001 saying the video was normal I had to see what would happen.
It warmed up to about 160 and then dropped back down as seems normal for my boat. The thermostat works and apparently water is circulating. Whew!
I am one happy camper.

Perhaps after the season I'll take a bunch of stuff apart and see if I can find any more rubber.

Thanks everyone!