DUI distributor wiring question.
 

Installed a new DUI distributor in my BBC, replacing a factory Thunderbolt V ignition, and trying to find a good source for power to the distributor. Tried it at the starter solenoid, but the solenoid is only 3 lug and the small post apparently is only hot when the starter is engaged. Engine would start up, but quit when I released the key to the run position. I am going to double check it with a voltmeter, tomorrow when I go up to my boat.

Where is the best place to connect a 12 ga. wire for power to the distributor?

Wondering if I can I run a power wire from the slave solenoid direct to the distributor? Wires from the ignition are purple, but they are somewhat smaller than a 12 ga wire, but there is a red/purple wire connected to one of the small terminals and I think it is hot when the ignition is in the run mode (again, will check it tomorrow). Red/purple wire is fused and runs from the ignition switch to the alternator, circuit breaker and slave solenoid. If this terminal is hot when the ignition is in the run mode, would this be an adequate location to obtain power for the distributor?

A friend suggested that I use the existing 12v (+) coil purple wire for power. This wire is not a 12 ga wire (but none of the purple wires in this harness are), and is probably a 14 or 16ga wire. With a run so short, will a 14 or 16 ga wire provide enough voltage to power the distributor and provide 12+ volts?

Unfortunately, electricity and circuits are not my forte, so sorry in advance for the uneducated question. Any info and help would be appreciated.

Thanks

just hook up a relay..use the existing ppl wire to trigger the relay and grab power from the starter but fuse it with a 30 apm fuse..use this scamatic but the fuel pump would be the dist..http://i959.photobucket.com/albums/a...boschrelay.jpg

When I had a Dui in my 496 I spliced directly into the purple ignition wire and never had an issue. No need to over complicate things.

running one now, just to factory ign wire

Fixx - I will do that if I can't get power any other way. Thanks

Black Baja - Thanks, I always over think things, when I'm not sure what I'm doing. If you spliced into the ignition wire somewhere, couldn't I just use the existing purple wire that went to the (+) side of the old coil? Did you splice in with a 12 ga. wire?

Ezstriper - Where did you splice in or did you use the existing purple (+) coil wire?

If the old TB V was an HEI ignition and ran off the smaller purple wire, shouldn't this DUI run off of it also. I know they say that it should have a 12 ga. wire, but..... Man, here I go again, making this more complicated than it should be. I just want to be sure that I am going to get 12-14 volts to this distributor. Heading up to check this out today. Hopefully, I will get it straightened

Went up and checked wires with the voltmeter. The existing purple (+) coil wire was putting out 12+ volts with the key on. Sooooo, I tapped into it and hooked it up. Cleaned everything up and gave it a go. Lit off almost immediately. Set the timing and she ran like a top on muffs. Will put it in the water next week and see if she still runs good.

I appreciate the responses here that made it a bit easier to go ahead and do it. Thanks

Here is a good .pdf of popular black motor wiring schematics that could prove valuable to have in one's computer boat folder: http://www.boatfix.com/merc/Techbk/94/94hg4d.pdf

There are more on the net of course, if you do some searching.

:drink:That's what I said i did on the Checkmate Forums. My feelings aren't hurt that you did not trust me. Glad it worked for ya.

Sorry, it's not that I didn't trust you, I just didn't understand your explanation of where you got the power. I took it that you somehow plugged into a flat plug in the EFI harness and that threw me, since mine is carbed. You threw me another little curve with the additional wire for the oil pressure alarm out of the harness. As I said, I am electricity challenged and I just couldn't grasp it. I kept thinking about the ignition module and the knock sensor harness plugs in my boat and didn't know if I could use the purple wires there. I finally realized that all the purple wires were the same size (DUH!!), so I opted for the existing purple (+) coil wire that wasn't being used. All that worry for basically nothing. I kept reading everywhere that the DUI had to have a 12 ga. wire for power.

Oh, and you were certainly correct. If you over think it, it does become more complicated than it has to be and will drive you crazy. I have spent hours searching for info about this.

Next time (if there is one), I will ask more pointed questions and try to get it straight in my thick old head.

Thanks

used several of the large cap HEI's I always buy the correct connectors from summit splice them to the power and tach and roll on...

Pep boys has the pig tail if you are in a pinch. And have one local...

Was just joking. I also spent hours trying to get it right. The best part of these forums for us DYI guys is getting good different solutions from the "experts" then sorting out what works best. Much better than paying good money and not understanding what the tech is charging you for.

And that's what happens with some people on the subject of oil on every motorsport / hobby forum on the internet.

Overthinking can make things mind boggling with no way out.

LOL.

please don,t get them started again,lol.

I realize this is an old thread but this is where the search function lead me. I'm hoping some of you are still active. I've gathered that its ok to just wire the DUI unit into the factory ignition wire. My question is in regards to the factory Mercruiser ignition control and knock modules. Can I leave them plugged in and expect them to function as advertised?

Thanks in advance and again my apologies for resurrecting a dinosaur.

No, you need to get them out of the system. The DUI is self contained. What happened to your TB V? They don't fail often.

Thanks for the reply! The boat is an extremely low hr boat for it's age. However, previous owners neglected to perform routine maintenance under the mindset of "it's got low hrs." With that being said, cap and rotor, coil, plug wires and more had never been changed. I had run a DUI unit on a ski boat years ago and had great results. However, I was able to just hook up battery/tach and roll. What will I need change on my setup to run the DUI unit?

I read that above and I guess I just had a specific question in reference to how you had the relay wired.

Was it like this?

85 - PURPLE
86 - GND
87 - TO DIST
87a - NOT USED
30 - BATT+