Your alternator/voltage regulator may have took a dive. Pull your dipstick first and check for level/water. If it's normal "chances" are you won't have to pull plugs, look elsewhere.

Get a scantool on it. Can't get to one? Check all the simple stuff like connecters including the main engine harness connector. Take it apart, and snap it back in. Check others as well. May be a grounhd in the transom harness. Do a search here for all 496 issues and there's a post concerning the harness as well as other very informative angles.

The other simple issue could be fuel related. Pull fule filters and pour into a glass pickle jar or something and let set for a bit to see if water or other junk shows up. Change them anyway. Change the inline filter too. The one between the boost pump and fuel tank. Might even want to go thru the little bit trouble of popping a couple injectors out to see if they have junk in them.

All stabs in the dark without being able to get a scantool on it, but also likely suspects.

Rob,
Before you do anything else, take everyone elses suggestion and pull the plugs, then turn the engine over to see if there is any water in the cylinders. A cylinder full of water will very easily bend a connecting rod if you try to start it :( Do that check before you do anything else. It could be a blown head gasket, which is not that terrible a repair, but if it hydrolocks and bends a rod ....... :angry-smiley-055:

Pulled the plugs last night, and the very last one I pulled I believe # 7 had water. I turned the engine over and more water shot out. I sprayed wd 40 in the cyl. I put plugs back in hooked up water muffs and the engine started. It did however have a miss, only running on 7 cyl. after testing I found that # 7 cyl was dead but I do have spark on #7...also when the engine was running I didnt hear any noise....

Ok guess its time to pull the heads. I would run a leak down test first but these engines are easy to take apart.

Ouch! Wish it would've been something more simple. Good luck.

Cracked head/blown head gasket on closed cooling would mean anti freeze not water in the cylinder
Are you loosing coolant out of the resevoir or has the level dropped?
Or more than likely it would have oil in the coolant resevoir.
Did you happen to look at what came out of #7? If it was anti-freeze then its a head gasket?
If its water I would say more along the lines of a cracked manifold or riser.
You'll take the riser, manifold off before you get to the head so sheck that manifold out for a crack before you go for the head.

If you loose the intake valve train only such that the intake valve does not open but the exhaust valve still does obviously that cylinder will not fire plus that cylinder will suck in sea water from the wet exhaust. Personal experience. A simple compression test will tell that story.

It was water not dex-cool... no water in oil, no oil in coolant reservior.
I did restart the engine on the muffs after I drained the water from the cylinder. If were cracked manifold or riser wouldnt it refill that cylinder again ????

yes if its cracked it will refill again. If the manifolds were cold when you started up the crack may not have opend up though. Did you check again for water in the cylinder after you were on the hose? I would compression check first. If it is a valve problem you won't have much at all. A bad valve or cracked manifold would be unlikely out of stock 496. Since it was 7 all the way at the back of the manifold at the lowest spot I would think would be more like water renentering? Do you have silent choice? Also check and see what code was set when your alarm went off. If its port manifold temp or water pressure you might be onto something.

496
 

Rob...What did you find out. It is important for people asking for help to follow up with the cause and solution so we all can learn.

Chris