1979 merc 40 wiring questions

[MacDaddy21]

I have a 79 merc 40 hp with the external harness plug on the left side of the motor. I want to know if I have to use the plug or if i can cut if off and just run wires straight in the motor through that plug hole and to their destinations. Thanks in advance.

 

[carholme]

Re: 1979 merc 40 wiring questions

Wiring the external harness direct to the destinations on the engine will make things difficult when you want to remove the engine from the boat. Why not do what some manufacturers do and find a good access point on the engine, mount a terminal strip and run your engine wires to that strip. Then run your external harness through the cowling and mate them to their system wires at the same terminal board.

Then, all you have to do to remove the engine from the boat is undo the external harness at the terminal strip.

Gerry

 

[carholme]

Re: 1979 merc 40 wiring questions

Thought I would add a picture of a Chrysler to show you what I meant:

http://img192.imageshack.us/i/1000362w.jpg/

Gerry

 

[MacDaddy21]

Re: 1979 merc 40 wiring questions

that sounds like a pretty good idea, but where would you reccomend buying a terminal strip with big enough holes to fit the larger gauge wire?

 

[carholme]

Re: 1979 merc 40 wiring questions

Not too sure which wires you are talking about that are so large. If you mean the battery cables, they are simply taped to the outside of the engine harness and run up into the cowl in the same manner and direct to their destinations. It is best to have these, one piece from the battery to their connection points.

The other harness which contains the system wires are end stripped and terminals crimped/soldered to them to mate, at the terminal strip, with their mating wire from the engine system.

Barring that I may not understand what you are driving at, if you have a marine dealer in your area, just tell him what it is that you are doing and he should be able to supply you with a terminal strip. Just tell him how many posts you want on the strip.

Gerry

 

[MacDaddy21]

Re: 1979 merc 40 wiring questions

okay that makes sense. I got a strip and will finish the wiring tomorrow. thanks for the help

 

[MacDaddy21]

Re: 1979 merc 40 wiring questions

started tearing into the plugs today and I have run into some issues with the wire colors coming out of the internal harness compared to what is on the external harness. there are 7 wires plus the battery cables on the external harness, then there are 4 wires plus the battery cables on the internal harness. however, on the internal harness, one wire (either a salmon or orange color) has 2 wires that funnel down to only one. I found a diagram online for a 1979 mercury 402 that seems quite accurate (With the exception of a tilt stop switch), and it shows that I should have a grey wire in the internal harness that goes to the choke solenoid. I will attach a link of the diagram and maybe someone can point me in the right direction. I want to continue with the terminal strip but i do not know which wires on the internal harness meet up with the external harness wires on the strip. I can post all the wire colors in each harness if that helps.

http://www.maxrules.com/oldmercs/Wiring/1966ona/24.pdf

 

[carholme]

Re: 1979 merc 40 wiring questions

Mac;

1. What is the s/n and model number of your engine, if you have it?

2. Is it electric start?

3. Are you using a dash mounted tachometer on your boat?

Gerry

 

[MacDaddy21]

Re: 1979 merc 40 wiring questions

S/n: 5253808
I don't have the model number.
It is electric start, and I do have the wires set up for a tach and I will probably get one at some point.

 

[carholme]

Re: 1979 merc 40 wiring questions

Mac;

Looks like it started life as a pull start and then modified to electric. It is a 402 (40) and here is the parts list if you don't have it.

http://www.crowleymarine.com/mercury-outboard/489.cfm

It sounds like they have used a standard Merc external harness which should contain 7 wires coloured as per the 402 wiring diagram.

Does your engine internal harness wire colours match the 402 wiring diagram?

Gerry

 

[MacDaddy21]

Re: 1979 merc 40 wiring questions

the internal harness colors do match with the exception of the gray wire. I cannot find one coming out of the plug

 

[carholme]

Re: 1979 merc 40 wiring questions

Mac;

If you look at your engine what colour is the wire coming from the choke solenoid as that is the one which will match the gray wire in the external harness.

Sorry this is taking so long but I don't want to give you wrong information.

Gerry

 

[MacDaddy21]

Re: 1979 merc 40 wiring questions

It is hard to tell what color it is due to the fading, But it looks to be whitish/pink. It is possible that it was gray at one point in time. If you can tell me how to upload pics I can post one of the internal harness plug

 

[carholme]

Re: 1979 merc 40 wiring questions

Mac:

Go here and upload your photos to that site. Press the Browse button and it will allow you to select where the phots are on your computer. Select where they are and press Open and then Upload on the Image Shack page.

http://imageshack.us/

Once you have the photo there, it will give you a link that you can use here. In the icons above the message you will be typing, if you pass your mouse along them, one will say "Insert Image". Click on that and it will provide you a window where you can paste the link which you obtained from Image Shack.

If you have problems with that, just post the link to the Image Shack page where you left your photos.

Gerry

 

[MacDaddy21]

Re: 1979 merc 40 wiring questions

Gerry,

The picture is on my iphone, and I just realized it really didn't turn out very good. so I will have to wait until tomorrow to use a camera to take a better picture and upload it. thanks for all the help, please hang in there. I'd really like to get this figured out.

Tyler

 

[carholme]

Re: 1979 merc 40 wiring questions

Tyler;

No sweat. Tomorrow I may be busy blowing snow but we'll get it done.

Gerry

 

[MacDaddy21]

Re: 1979 merc 40 wiring questions

Gerry

here is the picture of the internal harness plug. it is still sort of hard to tell which color is which, I will try again tomorrow. let me know if this is sufficient.

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[carholme]

Re: 1979 merc 40 wiring questions

Tyler;

That will have to do. I am going to try and get a drawing done today or tomorrow.

My wife is in Toronto as she had a hip joint replacement on 24 Jan and it went wrong, so she had to have another one implanted. They will try to fly her back north today or I will leave early tomorrow morning to pick her up. If I have to go, it is a 700 mile round trip so don't worry if you don't hear from me for a day or so.
Check your PM.

Gerry