1999 Mercruiser alpha 4.3l 2bbl engine wiring harness question

[Gkesel]

I have a 1999 Maxum 1800sr with an alpha One 4.3L 2bbl. S/N 0L096618.

I finally have replaced the motor that I burned up when I decided in 2011 to improperly winterize and then, thinking I was MacGyver, bypass the oil pressure switch that was trying to tell me something was wrong. Ended up burning up rear main and back two rod bearings. Lesson learned, albeit the hard and expensive way.

Anyway, am in the final steps in replacing this engine just gotta finish wiring, fuel, and fire this baby up!!

However I have run into an issue. On the wiring harness that is on the engine I have two wires that I cannot identify. One is on the port side by the coil, a black wire with a "o" electrical termination, 18-16gauge. It looks like a ground point for something, but I cannot determine where to mount it.
The other is in the starboard side near the choke, also a black wire but with a flat blade terminal. Also 18-16gauge.

I cannot find these wires specifically in any wiring diagram that I find.

I have attached photos of each.

Your help is much appreciated.

-George

 

[alldodge]

Being black they are both grounds. I believe this one goes to the back of the engine and is grounded against the block along with the battery cable. There should also be one going from the same bolt to the transom plate to ground it

 

[Gkesel]

Being black they are both grounds. I believe this one goes to the back of the engine and is grounded against the block along with the battery cable. There should also be one going from the same bolt to the transom plate to ground it

I don't think that's where it goes. The wire appears in the photo much bigger than it actually is. The terminal is the same size as the purple and gray wires going to the coil. Does it land on the coil? Or perhaps on the ignition module mounting screw on the port side exhaust manifold?

 

[alldodge]

I don't think that's where it goes. The wire appears in the photo much bigger than it actually is. The terminal is the same size as the purple and gray wires going to the coil. Does it land on the coil? Or perhaps on the ignition module mounting screw on the port side exhaust manifold?

Being that small then I agree it won't go to the block. It does not go to the coil, putting it there will cause the coil not to work. I would put it on the ignition module, it does need a good ground to work properly.

The one on the starboard side, do you have a switch or your shift plate for natural or interrupt?

 

[Gkesel]

Being that small then I agree it won't go to the block. It does not go to the coil, putting it there will cause the coil not to work. I would put it on the ignition module, it does need a good ground to work properly.

The one on the starboard side, do you have a switch or your shift plate for natural or interrupt?

Well, now that I look at it, the wire on the port side doesn't seem to be long enough to mount on the ignition module. Also, where I thought it was suitable to mount doesn't appear to be a ground connection--the body of the ignition module is molded plastic.

On the starboard side, there is the shift interrupt switch that connected to a white/black wire and a black wire with barrell connectors. Also near this is the choke which is landed with a black wire grounded to the choke housing and a purple/yellow wire with a female flat blade connector.

I'm still not sure where these wires go, but I greatly appreciate your input.

Thanks,
George

 

[achris]

One can get connected to the body of the distributor, the other can be insulated and tucked away. Merc, like most car makers, use generic harnesses, so those connection will be used on a different engine configuration...

Chris........

 

[Fun Times]

The black wire in the back, Does it look like there was ever a nut holding it down? I'm 99% sure it's main use is for the mercathode system which would have been an option on your engine package.
http://www.bing.com/images/search?q=mercruiser+mercathode+system+wiring&F
http://www.mercstuff.com/bravo3corrosion.htm

The other wire would have been for another style carburetor that utilized merc choke part number 809066 that looks more like these, http://www.bing.com/images/search?q=809066&FORM=HDRSC2

Hope this helps, good luck.

 

[Gkesel]

Thanks for your input.
Fun Times, I think you're right about both cases, especially the choke setup. I have not connected these wires to anything and the engine fires up!

The bad news is that I cannot get this baby to idle, at any rpm below about 1000. She runs so smooth throughout all rpm ranges but refuses to run at idle. I've adjusted the timing, right at 10?btdc. I suspect there's no fuel getting through the idle circuit. I rebuilt the carb myself(cringe), as it sat with ethanol gas in it for several years. I thought I did a pretty good job, but I wouldn't doubt any misdoings on my part. I've replaced the fuel filter, and put in 10 fresh gallons of fuel, with marine ethanol treatment. The gas tank was completely empty before I put gas in it, was sitting empty, but not cleaned for 4 years.

I realize this belongs on a new post, which I will start right after, but do you have any ideas?

 

[achris]

Use compressed air to blow out the carb circuits? (PROPER compressed air, not that 'fluff in a tin'.)