Was having a good day until...
 

Ignition issues. G*d Damm!t!!

Cruising along at 3K, rpm dropped a touch followed by two rapid pops through the supercharger. The engine stalled immediately, started up but was hard to start and seemed to be missing. Limped it back to the beach, cracked open a beer to celebrate getting out regardless of the issues, and let her sit.

Twenty minutes later she won't start so I mess around with the module plug... starts up fine, seems to be running great, so head back to the dock. Running great still, turning about 3200-3300, exact same rapid fire pop through the blower, and now dead. Getting towed back by my buddy as I write this. Great.

Factory Merc Thunderbolt with V6 module and an older but new MSD 6M2 (6490). It's not the MSD, I bypassed it. Assuming the module died.

What can I replace this with tomorrow morning to be back on the water?! Delco TBI? Will that work?

I'm so f'ing pissed right now. I know I should have replaced this the last go-around.

Throw an HEI mechanical advance in and go. Worse case scenario lock in at 32 deg. Will get you through the weekend anyway. One ignitition and tach wire - time it and go.

Coil

It a new coil.... doesn't mean anything but I don't think it's that.

I don't think a large cap hei will fit with the blower.

If none of the easy stuff fixes the problem, I would do a leak down test. Might be something like a broken valve spring.

It never seems that way does it. If it does it certainly isn't with me. Wouldnt it be nice if it was a coil... I can think of maybe one in over 30 plus years one went bad on me.

Pretty much rules out valvetrain issues from what you described. This seems to be a common thread lately. You checked module etc grounds I assume. Distributor tight and not moving around. Be nice if you had a module you could try. Any luck yet?

Check fuel tank vent.

I think you're right on with it being ignition, I've seen more and more modules going bad lately, we've finally found the lifespan of merc tbolt modules

Fuel pressure was a steady 8 lbs. the vent is free.

Valvetrain is good. About 2/3's thru the tow I was able to get her started. Ran around a little near the dock, then put her on the trailer.

Either the module is getting hot and going on the blink, or it's a connection issue. I'm going to find a TBI distributor, and get her set-up.

what coil are you running and how old is it?

Mike,

It was a brand new Merc coil.

Upon deeper inspection, I found that the module had lots of corrosion coming out from between the terminals within the connector base. I guess it's had some water intrusion.

I went and picked up a MSD 85551 (not so much an MSD fan any more but this worked), changed to a weather tight connector, locked the advance, ripped out the Merc stuff, and got her back up and running in about an hour or so. Timimg is locked at 30.

I ran her for a few hours yesterday, and no issues.

tom,glad you did not have a damaged engine and that you are up and running.try setting your total advance at 32,i think you will have a happy engine with a little more advance.

I was thinking the same thing... thanks for confirming my thoughts Mike!