Ground Wire Fire, Need help.

[tjohnson43.97]

New here and not to be rude, but wish I wasn't because that would mean I didn't have engine problems.

I have a 1994 40 hp 2-stroke main power that when I went to start at the the boat dock last night began smoking. It was pouring rain and just launched the boat at the Seward public boat launch. The motor was barely turning over, so I immediatly assumed battery was low, so switched to dual battery status.

Still trying to crank it over for about 10 seconds, smoke became abvious that it was not the typical oil burn smoke, but it was a fire. The housing on a ground wire had caught fire and quickly burned itself off before I could get my fire extinguisher out. Long story short, I drove the disapointed wife and kids home home last night with a busted 4th of July weekend and boat.

Just a bit of background. The motor ran fine just the last weekend outing. All I did this past week was replace a transducer and upgraded my fish finder. I removed an older GPS unit and mounted my downriggers.

Everytime I try to start or even bump the key to start the motor, I can see the wire heat up immediatly. The wire appears to be a ground connecting from the motor bracket back to the motor shaft, about 6-inches long and maybe like 14 gauge wire. I see there two others like it in other areas. Seed pictures below.

Any help would be greatly appreciated. If I can get this resolved, I will take the family back out to catch some silvers. Thanks again!

Thanks
Tjohnson

[rodbolt17]

thats not a ground wire, its a bonding wire.
you do have a bad battery ground issue.
double check all your cable connections and go play.
that bonding wire was not designed to carry a current load.
if it has trim and tilt also double check the relay ground.

[tjohnson43.97]

What is a Bonding Wire do?

Thanks for the advice rodbolt. I will heed your advice and tripple check my cables. What does a bonding wire do? Does it need to be replaced even though the housing has burned off?

Tjohnson

[tjohnson43.97]

Okay, checked all cables

So I checked all cables and searched for loose or damaged wiring and did not find anything. I fired up my 9.9 yamaha kicker which is on the same battery connection and it started without problem. not sure what the relay ground is, but checked all wiring i could find and all seemed tight and witout physical damage. the bonding wiring is still heating up as soon as the motor is bumped over. Any thoughts??????

Tjohnson

[jb123]

feel ground wire after trying to start, if warm to touch , cut back 6",relug and retry

[99yam40]

Use a meter and find the bad negative connection.
looking and feeling them will not get it done

Apparently the bonding wire is a better ground than the negative cable

[casey1240]

TJ -

The only thing you have done according to you is to add/modify your wiring configuration since it last ran ok. What I would do would be to disconnect everything from your batterries and reconnect your motor separately to just ONE baterry making sure you have positive to positive/ neg to neg. Don't go through your batterry switch. Then try to start it. If you have the same results, then it's time to trace the voltage via a meter. if you have one, or start looking for a good tech.

My thought is that you have introduced some higher voltage via your battery set-up. Could be 24 volts if wired incorrectly or your battery switch is faulty. Just some thoughts. Good luck.

[seahorse5]

Check the battery ground cable where it attaches to the motor. There could be corrosion or discoloration under the terminal, loose connection, or even a bad cable. Inspect it all the way to the battery and check that connection also.

[rodbolt17]

bonding wires simply hold two parts at the same electrical potential. that way one part wont start eating another with electrolysis.
wont hurt that the insulation is missing.
you do need to find your bad ground path.

[tjohnson43.97]

Got It! Thanks to all!

So after spending some time isolating, cleaning and completing a close examination, I found the fault in the negative ground cable. It was located right where both the pos and neg cables enter the motor housing. It appears the negative was almost severed in half. Don't know how that could of happened or how I could have missed it in earlier inpsections, but that was the problem none the less. After making new cables at West Marine ($68)and a few hours of cleanup, we are back up and running. heading for those silvers once again out of Seward, AK in the AM. Thanks to all who offered advice and assistance.

Casey124 and Seahorse, you were the winning methods of finding the problem. I'm sure this was a minor problem to most of you, but it sure felt like a major one to me.

Thanks again and if there is anything I could do to help another, let me know.

TGJ

[tjohnson43.97]

Got It! Thanks to all!

So after spending some time isolating, cleaning and completing a close examination, I found the fault in the negative ground cable. It was located right where both the pos and neg cables enter the motor housing. It appears the negative was almost severed in half. Don't know how that could of happened or how I could have missed it in earlier inpsections, but that was the problem none the less. After making new cables at West Marine ($68)and a few hours of cleanup, we are back up and running. heading for those silvers once again out of Seward, AK in the AM. Thanks to all who offered advice and assistance.

Casey124 and Seahorse, you were the winning methods of finding the problem. I'm sure this was a minor problem to most of you, but it sure felt like a major one to me.

Thanks again and if there is anything I could do to help another, let me know.

TGJ