# Outboard Power Wire(s)



## caucoin (Dec 24, 2021)

Anyone have any recommendations for the best type of fishing wire to use for replacing (changing out) a corroded power wire from the 115 Yamaha to the battery? Its a 2 guage wire. I snipped off a thumbs length of corrosion and re-attached the lugs and I'm still getting a power reduction while running approx 3500 rpms or higher down to limp mode, or 1700 rpms. Kind of frustrating seeing as I just bought it, but this wire seems to be the smoking gun. Before we started cutting wires, we ran it at 3500 rpms, and shook this power wire back and forth to purposely bring the engine down so we could confirm our problem. Well, it depowered so low, it killed it, and wouldn't restart - confirming we found the correct wire and could rule all else out as the source of the problem preventing the engine from running properly. We were able to get the wires back into place long enough to limp back home and begin cutting the ends off and cutting out the corrosion. It was pretty bad. There were only about 10% of the copper wires touching and the rest were hanging off from corrosion.
As soon as we tested the newly termilaled wires, with new lugs and heat shrink, we tested it and ran it again. It was 90% back to health. The outboard ran for about 5 minutes at 4100 rpms before knocking itself down to limp mode again.
So...I want to replace that entire electrical power "run" from the outboard down to the battery. Never done it before, and want to make sure I can fish the new wires back through the holes after I pull the old ones out, and attach some strong wire, braid, or mono to make sure I can.
Any help is appreciated. 
Thanks


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## lemaymiami (Feb 9, 2007)

A lot will depend on the size of that motor (bigger motors - larger gage wire... Talk to whoever does your motor maintenance (dealer?) and find out the exact specs for that main power cable (and if you're replacing it I'd be doing the negative side as well..). Matter of fact it may be a ready made part you can buy - meant for your motor, with both positive and negative cables in a single unit - ready to install... If you're making your own from scratch you want tinned copper wire - nothing else... and you want the correct sized lugs for the connection with the right sized heat shrink to seal them up and prevent (as much as possible any water intrusion into that nice new cable...). at each end of each cable to make sure you passing all the power from the cable to the battery (or motor end). Remember as well that heavy battery cable really needs a solid crimp for the lugs (something you might want your dealer or a marine electrician to do for you if you're not sure you can do it properly).

"Aren't boats fun?"


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## marshrat (Feb 22, 2018)

Are you asking how to actually "fish" the new battery cables through the chase? Just use electrical tape to attach the end of the new cable to the old cable and pull it through. Two birds, one stone. 

If you're making your own cables, Bob's advice above is spot-on.


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## Smackdaddy53 (Dec 31, 2012)

You need to refer to a voltage chart to determine wire gauge necessary to carry voltage a certain distance first and foremost to be sure you have the correct gauge wiring then confirm battery health and all connections are solid.


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## andy race (Jan 15, 2018)

I know its always tempting to use automotive battery cable which is SAE rated, (society of automotive engineers) done it myself a few times but if you can find the same size wire in AWG, (american wire gauge) it will be a finer or smaller stranded wire that is best if you can find it tinned the entire length, this will minimize and prevent corrosion. As previously stated you need to match amp draw to wire size, the same size wire in SAE or AWG probably will not have the same circular mills and amp rating, so you may have to adjust, its just the AWG is much better for marine use. I've had SAE copper turn black the entire length of cables and wires. Again tinned is best and keep in mind loose connections is the bane to either wire in any application


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## permitchaser (Aug 26, 2013)

Do forget dielectric grease or spray, I have both, and coat all ends. They sell a chase puller at Harbour Freight. Make sure you use your old wires to pull the new ones. Make darn sure however you attach your wife to pull so that they won't come apart. Nothing more frustrating than have your pull wire come apart deep in the chase
You may need a new battery


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## SkiffaDeeDooDah (Jan 20, 2020)

All good advice above ^^






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## Smackdaddy53 (Dec 31, 2012)

I leave a piece of paracord in the chase to pull new wire back through.


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## Alex from GA (Jun 14, 2021)

Tape a piece of doubled nylon paracord or other heavy cord to the cable and pull it through. If it'll fit, fold the cable over and tape it to attach one of the paracord pieces and pull it through. Leave the other in the chase for future use. Electrical tape is your friend.


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## Eirus (Dec 15, 2021)

lemaymiami said:


> A lot will depend on the size of that motor (bigger motors - larger gage wire... Talk to whoever does your motor maintenance (dealer?) and find out the exact specs for that main power cable (and if you're replacing it I'd be doing the negative side as well..). Matter of fact it may be a ready made part you can buy - meant for your motor, with both positive and negative cables in a single unit - ready to install... If you're making your own from scratch you want tinned copper wire - nothing else... and you want the correct sized lugs for the connection with the right sized heat shrink to seal them up and prevent (as much as possible any water intrusion into that nice new cable...). at each end of each cable to make sure you passing all the power from the cable to the battery (or motor end). Remember as well that heavy battery cable really needs a solid crimp for the lugs (something you might want your dealer or a marine electrician to do for you if you're not sure you can do it properly).
> 
> "Aren't boats fun?"


Thanks for the feedback. Just got done with crimping, heatshrinking and attaching the new lugs. Everything is reattached I was able to feed that large 2 guage wire through from the back hatch under neath to the center console. All the cockpit lights, navionics, trim tabs engage and power on when I flip my 2-position switch from "off" to "on".... however, "no joy" from the engine. This is a first. Before I disassembled everything, I always had power to the engine. It would lower/raise up, as well as start up on a dime. I will double check my terminal posts to make sure my "run" is correct. Theres a terminal junction in the back hatch that has several wires on each terminal post. Perhaps this is where I have a wire or two out of place. Lucky for me, its the hardest to get to, physically. 
Lastly, I just watched an interesting youtube video of someone with a similar problem Im having after rewiring the power wires, and he had to use a rubber handled screwdriver and connect the terminal posts to get the engine to start up. After he did this once, he said it always started and ran perfectly. I will try this if needed. It just doesn't really make sense that I have to "jump" the connection like that. Thanks for the response.


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## Eirus (Dec 15, 2021)

marshrat said:


> Are you asking how to actually "fish" the new battery cables through the chase? Just use electrical tape to attach the end of the new cable to the old cable and pull it through. Two birds, one stone.
> 
> If you're making your own cables, Bob's advice above is spot-on.


Got it. Thank you. That part was successful. Now Im trying to figure out why I suddenly have no power to the engine. Maybe I have run the wires on the junction terminal on the opposite posts.


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## Eirus (Dec 15, 2021)

andy race said:


> I know its always tempting to use automotive battery cable which is SAE rated, (society of automotive engineers) done it myself a few times but if you can find the same size wire in AWG, (american wire gauge) it will be a finer or smaller stranded wire that is best if you can find it tinned the entire length, this will minimize and prevent corrosion. As previously stated you need to match amp draw to wire size, the same size wire in SAE or AWG probably will not have the same circular mills and amp rating, so you may have to adjust, its just the AWG is much better for marine use. I've had SAE copper turn black the entire length of cables and wires. Again tinned is best and keep in mind loose connections is the bane to either wire in any application


Thanks. This is interesting. I am using a heavy 2 AWG Marine grade wire at 10ft length for this 115 yamaha, which is the exact identical wire I pulled out from the boat. Perhaps it is too thick, according to your logic and the chart below. The breaker switch says "50 Ampere" so that must mean I am definitely using too heavy a power wire. I wonder why it was setup like that. I bought it like that, so I guess thats why. According to the chart/logic I should be using an 8 guage wire. 
No wonder I got a lot of wierd looks asking for 1 or 1 guage lugs from the hardware store, West Marine, and other stores like it.


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## Eirus (Dec 15, 2021)

SkiffaDeeDooDah said:


> All good advice above ^^
> 
> 
> 
> ...


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## andy race (Jan 15, 2018)

actually oversized wire would be beneficial, less voltage drop , are you saying the engine and power trim/ tilt will not work after running new cables from the battery to the engine? thats what I thought your original post stated. Do you have a DC voltmeter ?


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## Eirus (Dec 15, 2021)

andy race said:


> actually oversized wire would be beneficial, less voltage drop , are you saying the engine and power trim/ tilt will not work after running new cables from the battery to the engine? thats what I thought your original post stated. Do you have a DC voltmeter ?


I don't. My brother is a mechanic and he suggested I get one to see what my output is. Then I can read that chart more accurately. To answer your question, yes. I am now not getting any power to the engine and power trim/tilt. It worked before I started fiddling with it. I am willing to bet I have my wires crossed - literally. I'll check again in the morning. Its just a nightmare getting back underneath that back hatch to adjust anything on those terminal posts.


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## SkiffaDeeDooDah (Jan 20, 2020)

Eirus said:


> Very helpful chart. I may in fact be using far too big a wire here


For cranking amps load, I think you're good with 2-ga wire. 4-ga maybe, but I'd feel better with the 2-ga. Better to have more capacity, than less.


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## andy race (Jan 15, 2018)

where are you located, anywhere near central fl?


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## Eirus (Dec 15, 2021)

andy race said:


> where are you located, anywhere near central fl?


The Keys


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## andy race (Jan 15, 2018)

if you want you can call me tomorrow, I've working in Tampa since early this AM and just got in not long ago.. 352 274 0419


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## Eirus (Dec 15, 2021)

Update: I checked the entire run from the battery, to my 2-position switch, to the junction terminal in the back hatch, then finally to the engine. All had a reading of 12.7v on the voltmeter. I checked the fuses and found a blown out 50 AMP main engine fuse and ran up and got the last one in stock near me. That fixed the new issue I had created for myself in the process of rewiring the power wires. Power tilt/trim is functioning again, and I will run the boat in the water tomorrow morning to see if I can't get back up to cruising RPMs without it kicking down to limp mode. I believe it should.
Thanks for the help.


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## marshrat (Feb 22, 2018)

Eirus said:


> Update: I checked the entire run from the battery, to my 2-position switch, to the junction terminal in the back hatch, then finally to the engine. All had a reading of 12.7v on the voltmeter. I checked the fuses and found a blown out 50 AMP main engine fuse and ran up and got the last one in stock near me. That fixed the new issue I had created for myself in the process of rewiring the power wires. Power tilt/trim is functioning again, and I will run the boat in the water tomorrow morning to see if I can't get back up to cruising RPMs without it kicking down to limp mode. I believe it should.
> Thanks for the help.


That will happen any time you run wires to the wrong polarity- positive to negative and negative to positive. If you're lucky, that's all that happens.


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## Eirus (Dec 15, 2021)

In replacing wires, I damaged and loosened a terminal post. I overtightened the nut on the terminal post, heard a pop, and had broken the post off completely. Its a 2 x 5/16 Terminal Block (in a very difficult position to get to in the back hatch). Now I have to remove it and replace it. However, even with the two little screws out, the thing seems really well attached and glued on to the bulkhead. Not easy to remove. I have tried with pliers and it wont budge. Any suggestions? I really can't get a hammer and chisel back in there to try and pry or pop it off. Pliers dont seem to be making the thing budge either.


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## lemaymiami (Feb 9, 2007)

Here's one more lesson about power cable connections at the battery.... Today I was working off of of a 25 foot open fisherman with a shiny new Suzuki 300 (and yes, that's some power plant...). About 20 miles from Flamingo near the gulf coast we lost all of our electronics (and that motor was rigged strictly fly-by-wire so we were dead in the water). A check of the battery cables showed that the #1 battery had a bad cable, cracked right through and badly corroded about 3/4" from the battery post. In fact, it broke away in my hand when I pulled on it. No idea how we even got it to start that morning - it was that bad... 

What to do - broken cable - no battery lug end... so I stripped the insulation back about one inch, split the wire into two parts, placed it around the battery post, then added back a second cable with a good lug end and bolted it all down tight. Everyone grinned when all of a sudden we were back in business... Of course we quit fishing and made the long run back to Flamingo on this jury rigged repair... Like our marines say... adapt, improvise, overcome... Don't think anyone would enjoy a night out on the coast of the Everglades - just you and all the mosquitoes in the world... By the way if you call the Coast Guard, they'll send you a tow boat... but it will either come from Chokoloskee (35 miles) or Marathon, (more than 70 miles I believe) - and you'll be paying portal to portal... Pretty sure that works out to maybe four or five times what a tow out of the keys or Biscayne Bay would be...


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