3.0L Mercruiser electrical issue?

[Scooty Puff Jr.]

Hey guys,
I have an '87 Wellcraft 190 classic with a 3.0L Mercruiser. After bringing it out for the first time this year I had a weird problem. Unwinterized the boat, took the battery off of my battery tender started boat in a few seconds, run it for 10 minutes or so get all coolant out, done and done. Cool let's go to the lake.

So we get to the lake, boat fires right up. Drive about 2 miles go to slow down, boat stalls. It fires right back up, go to take off, stalls. Go to start up, I get one click no cranking. Accessories all work, radio works, blower works. So after checking all connections and sitting around with the anchor out for twenty minutes some guy comes by at mach 5 and knocks my anchor loose(very few rocks in lake, mostly mud). So panicked that I am going to get shoved into the causeway I give it a shot and whattya know it fires up and away we go. Drive to a more open part of the lake about 10 minutes away, go to slow down, boat stalls. Try to fire it up, a click and no cranking again. All accessories still work. This time after an hour of no luck I get towed to the docks. Put the boat on the trailer, just for the hell of it I give it a quick crank and the SOB turned over! Now it sits in my driveway, if I go out right now and throw it on the muffs and hose it will fire right up. I am afraid to take it back to the lake but I can't find anything wrong with it. I have the Mercruiser manual but I have run out of their troubleshooting techniques.
My battery shows a full charge on both my regular battery charger and my battery tender. I can't find any loose or broken wires or signs of corrosion.

Any ideas? Comments? Sorry for the long post but I don't want to leave out anything. Thanks guys

[Pete104]

Take the "cannon plug" & pull it from the "engine harness". That's the harnes that feeds the dash. You won't see any corrosion until you are looking at it real close. Clean both sides & push it back together. Only goes one way. It should have a hose clamp on it to help keep moisture out. If it didn't have one put one on it but don't overtighten it!

[dingdongs]

get battery tested down your local where they put a large test across the two terminals.if the battery is getting old replace it and if you can carry a spare one its a bonus.a cheap multimeter would not go amiss to see if you have power to coil or the starter or its solinoid is failing.remove all main earths to engine ,clean and silicon or vaseline them up and reinstall.

[fat fanny]

As dingdongs said you would be surprised what you don't see as being the problem physically removing and cleanin every connection is somewhat time consumming but worth every second. I removed my entire wiring harness last June and went through the whole thing inch by inch and tested each connection re-sealed,cleaned and lubricated just for a slight nagging miss which ended up being a bad connection to the coil.

[Don S]

Next time it decides to go bad, have your test light handy and try this.
http://forums.iboats.com/mercruiser-i-o-inboard-engines-outdrives/how-troubleshooting-your-engines-starting-system-167035.html