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Confirm wiring for 1978 80hp 800 mercury

S

surgemc

Member
I am rebuilding my motor and unfortunately, the previous owner re-wired the engine with only blue wire. I have stripped back until I found the original wires but as you can imagine they are not great and very faded. I will replace them at the same time. These are the colors i believe i have and what I think is their destination.
Gray - Choke solenoid
Black - small post on Starter solenoid and ground?
Yellow - small post on Starter solenoid
Red - large post on the Starter solenoid and + on rectifier
Brown - Rectifier
Orange - Switchbox
Is this correct?
Also where the diagram shows an earth symbol, such as where the black wire is split, should this be earthed to the block or the cowl?

Thanks
 
http://www.maxrules.com/oldmercs/Wiring/1966ona/30.gif Here's a diagram,hope it helps
The orange does not run the whole way from the controls to engine.It is the kill circuit.I took a jumper from the orange wire,and ran it through a small hole in the pan to the mercury tilt switch wire that connects to the switch box.I needed a kill switch.There is a hole about 1/8" in the bottom of the pan,under the wiring plug.
I would earth the black to the block.There should be several earth cables from the block to the pan
 
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Thanks for that. What i have had to do is bypass the connector plugs as they were too deteriorated to use, impossible to find here in Australia and too expensive to ship from the States. As the white wire from the control box doesn't continue on the engine side of the plug should i be connecting it to the black wires?
 
Nope,the white wire is 12v+,black is earth.There are two sets of connections on the switch-box.The white wire goes to switch-box,the terminals should colour coded.However that white wire should run all the way from the control box.Which control do you have?
 
I have the control box shown in the pic. My boat is at work atm so I can't check to confirm until Tuesday but I don't think I have any unused terminals on the switchbox but I still have the white wire spare on the engine side. The previous owner had done all the joins for the new wires right at the plug so it was difficult to confirm 100% what colour each wire was when I replaced them.
The reason each wire wasn't tagged was because the marine mechanic who dismantled the engine to replace the bottom crank seal , decided it was not worth repairing and he obviously thought he knew where each wire went. However I am enjoying having a go and doing it myself.
Thanks for your help so far.
 

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I used an identical control on my '69 Merc800 until I moved it to the Shakespeare.It was plug in and go,to install the kill-switch I had to put jumper on the orange wire to the distributor side of the switch-box.Does it have the cobra head?
 
Just reread you post,you should have a spare terminal on the switch-box.The brown wire now goes to one of the alternator/stator terminals on the rectifier,unless you have one of the old Mercury tachs
 
You have the CD type ignition I believe there are complete engine harnesses still available. The orange wire from the ignition switch is the only wire going to the switchbox and mercury switch. Do not apply battery pos to that wire or you will need a new switchbox. That is the kill wire and the ignition switch connects it to ground to kill the motor when the key is off. It is allways fun trying to sort out someone elses goofiness do not connect the battery until you are sure the wiring is correct.
 
You can allways disconnect the orange kill wire to test the ignition the only hot wires going to the motor are red to the rectifier and the choke wire when the choke is pushed the ignition is self supporting independent of the charging system. If you get the motor running just short the orange terminal on the switchbox to ground to kill the motor.
 
For your info the white wire coming from the ignition switch gets terminated at the plug it was used to power the old points type switchbox if you apply battery pos to the orange wire for a split second you will likely need a new switchbox.
 
haventaclue said:
Just reread you post,you should have a spare terminal on the switch-box.The brown wire now goes to one of the alternator/stator terminals on the rectifier,unless you have one of the old Mercury tachs
Click to expand...
I was on another planet.
The orange wire runs all the way through.As kimcrwbr1 says "Do not put 12v+" to the orange wire
 
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