Outboard Ignition Switch Wiring

jaboat1

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Joined
Jan 20, 2024
Messages
1
TLDR: I'm really not sure if I'm using the correct kind of wire to connect my boat's original wiring to my new ignition switch.

Hello. Got my first boat ever a couple months ago and the ignition switch busted so I bought a replacement. It's a 1982 Mercury 90 outboard. I followed some diagrams to match the wires to their proper terminals on the new ignition switch. Now when I turn the key, the starter motor spins but only a little bit. It does not spin fast enough to rise up and engage the flywheel. I did a bit of investigating with a multimeter to find that my starter solenoid was only receiving 3-4 volts when the key was being turned to the "start" position. (I'm guessing it needs more like 12v). So I go to my ignition switch and find out that the red wire connecting to the "B" battery terminal on the ignition switch, is receiving 12v a little inconsistently. In other words, sometimes it shows 12v and sometimes it does not. It is the main power wire that powers the ignition switch so I believe it should always show 12v when the boat's battery switch is on. So I figured I made a bad connection from the old wire to the new switch and it was dropping voltage. So I cut off the bit of wire that was in the crimped/heat shrunk tube and tested the raw original wire. Sure enough the original positive wire coming from the starter solenoid is showing 12v but the wire isn't long enough to make it to the ignition switch anymore. So my solution was to connect it to a strip of wire from Lowe's and then connect the other end of that to the ignition switch. I did that and it is not showing 12v at the ignition switch terminal it is connected to. So it HAS to be my poor connection right? I originally tried soldering the wires together but after experiencing the same issue of not enough power to the starter motor, I decided to try the wire crimp heat shrink connectors instead. Am I missing something here or am I just screwing up the wire connections? My process is to strip both ends, stick them into the conductive tube, crimp them down so the tube has a tight hold of the stripped wire, then heat them up to shrink it all up. I'm not 100% if the old boat wires are 14 gauge but the wire from Lowe's is 14 gauge and they seem to match up relatively close. If anything, the new wire I'm introducing is slightly bigger than the original wire. I've spent a lot of time head scratching on this one after redoing the connection a few times so any help is much appreciated. It's fun having a beater boat to learn on, but I'm dying to take get it back in working order. Also I can confirm that the battery is fully charged, I've been topping it off with a charger before I try cranking. Thanks!
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
42,555
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My guess is there is a weak battery, corrosion or a bit of both

A fully charged 12V Bat should read close to 12.7V. Put meter probe across the Battery post, then crank motor and see if it stays close to 12V

If voltage drops low then need to start cleaning connections. Start with both cables and both ends. The Ground side is important
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,082
Some will argue, but the best electrical connection is a soldered one. That was how my '77 Merc ign switch was wired, and it lasted until I retired the control in 2021, but was still good at that time. I used/kept the boat in salt water, so I consider it to be a severe test of the solder method.

Boat wiring almost always has corrosion in the wire strands. The best way to clean it is with very fine sandpaper. Now flux up wire, connectors etc, and use a heavy (60-80W) soldering iron to really heat the connection and using rosin core solder, and let it flow into the connection. Now insulate.
 
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