** HELP - 2007 5.7L - DIED now won't start!

2007 Ski Nautique (206 - open bow)
5.7L PCM GM Vortec
625 total hours (150+ this summer)
We are in Maine - ski hard May - Oct - 150 hours this summer

Issue:
DIED after planing out! Warmed it up for 5-10 min while shuffling ski gear. Putted 2 minutes out of cove into open water. Plained boat out and it died. Paddled back for 30 minutes with 2 water skis.

Boat is meticulously maintained. Wires, plugs, cap, rotor, fuel filters, oil, marine stable, impeller...all done when they are supposed to and regularly. Like many of you, she is well maintained.

Before hauling out of water I checked the following: kill switch, spark, fuel pressure, fuel cell and filter, small inline fuel filter, plugs, wires, cap and rotor. Plugs, cap and rotor and a new coil were all less than 30 hours old. The boat had no issues ever until the cam position sensor went about 25 hours ago. That was replaced. I replaced the coil when I was trying to diagnose the cam position sensor issue which was professionally diagnosed by throwing the relevant code.

Mechanic (at a Nautique dealer) His Notes: "scanned the computer and found no codes and no sensors that show any readings that are out of parameters. I have changed the crank position sensor, cam position sensor and ignition coil and driver as well as the ECM with good known parts off of an engine in the shop. I have checked compression and that appears to be ok, I have also changed the distributor gear as it showed some pretty decent signs of wear. At this point in time it looks like there may be an internal issue with the motor probably leaning towards the camshaft but i would have to dig a little deeper to be sure."

"The motor is acting like it is being told when to inject fuel and fire at the wrong time, hence me thinking it could be a camshaft issue, which could also be a timing chain or gear issue or it could be the woodruff key on the crank that holds the bottom gear or the reluctor wheel on the crank for the crankshaft sensor. Basically I will need to dig into the motor and see if I can pin point it with going in as little as possible. The first thing that I would like to do is pop the exhaust and take the valve covers off, this will give me a good idea if the camshaft is doing what it is supposed to be doing on all cylinders. If that all looks ok then we will have to dig further and the next step would be remove the front drive accessories see if we can get the timing chain cover off. A lot of the time the motor has to be pulled due to the fact that the cover has a lip that sits inside of the oil pan and usually cant be removed without taking the pan off. "

Thoughts?!?!?

Here are 2 vids of trying to start it:
https://youtu.be/jYGKh-ha0bg
https://youtu.be/WyRo_gzty48

Since we are in Maine they are doing 500 winterizations and won't be able to look into my boat until December. It's killing me to store it broken.

Thoughts?!?!? Suggestions.

Thank you for your time.

Thanks for the reply. Mechanic didn't give me compression numbers.

He and I check fuel pressure separately. Not sure what he go but I just checked it right now...it's in my driveway...it seems fine...56. My PCM Manual says 57-62 @ WOT

Someone on an other forum site just suggested I do this...so I just did. Sprayed starting fluid down throttle body...tried to start it. It just made some sharp backfire like gasps (bad description)...but otherwise sounded like the video I posted. No luck.

By no means am I a mechanic. Agreed that starting fluid is not the best thing to use. But, if it didn’t fire up and run for a couple of seconds on starting fluid, I’d say your issue is electrical/timing. If it ran for a couple of seconds on starting fluid I’d say fuel issue.

Lol Pete. I copied and pasted it. Closing the camp. No neighbors and I’m reading the threads. I have to admit you guys rock with the advise. On that note, I’m assuming this is the 275 hp carbureted engine. If so or not, why all of the sensor replacement? I’m looking to up trade to a 206 and if there is a common issue I’d like to know.

Lol, my cutting and pasting skills on the iPhone are poor. I watched an engine with an air filter try to start.

Pull the valve covers and plugs. Roll the engine in direction of rotation until the timing mark approaches. Look at the valve train while you roll it.. #1 intake and exhaust rockers should be not moving (closed) and #6 should show both intake and exhaust rockers moving (overlap interval). If that is not happening roll the engine another 360* and look again as you approach the timing mark. If when on compression stroke and #1 pair is still and #6 pair are both moving together then the valve timing is close enough to run. This is called opposing valve method and actually is the way I choose to set rocker clearance because I get to set the valves in the actual firing position for that cylinder.
"one is knocking when six is rocking" and so on and so forth.
Pairs would be: 1&6 2&3 8&5 7&4 If they all check out and #1 keeps landing on the timing mark you have no (major) issue with your valve timing.
You should be able to land the engine on (or damn close to) the timing mark simply by watching #6 cylinder valve rockers.

Keno gave you very solid advice. Do that before moving forward.
Starting fluid is very volatile. I have seen many engines with broken pistons from starting fluid use.   I saw one 7.3L Ford Diesel that blew the entire intake manifold off the engine from starting fluid use.
I have starting fluid and use it very carefully from time to time but never spray a direct shot down a carb and then try to start the engine. Most of the starting fluid will go to very few cylinders and those will get a big gulp and when it ignites it is very harsh.
Parts break.   I hope you did not do damage to your engine.
If you need to use starting fluid have someone turn the key and spin the engine, then with it spinning spray a little at the carb or intake.   You should get instant results. If not, stop, you have other issues.   Even doing it this way the engine will knock and ping when it tries to start. Starting fluid works but is very harsh on parts.

A correction on my part, in my post above I said great advice given by Keno, no disrespect to him but the post I wanted to refer to was from Baitkiller. Sorry guys..
That simple advice will let you verify the basics are OK.