Bonding wires carrying current and smoking

[mawhins]

Hi all, I'm new here and have recently purchased a second hand tinnie. Its a 2000 Sea Jay Escape 4.45 with a 40HP Yamaha 3cyl 2stroke. She's a bit rough and the wiring was a bit dodgy so I bought a new switch panel and set about reconnecting existing wiring to the panel. That all went reasonably well and I took it out for a spin and everything worked although I noticed the motor was running rough, sounded like it was missing.

I went to flush the motor and began by connecting the battery (I have been disconnecting the ground cable at the battery when not in use as there's no isolator switch). The motor was at full tilt at this point. When I connected the ground the bonding wires on the leg of the motor started to get so hot the insulation on them was smoking. I disconnected the ground straight away.

I've gone over the motor looking for loose ground cables or chaffed cables particularly any that might be pinched when the motor is tilted but couldn't find anything.

Wanting to continue with the flushing I manually lowered the motor and tentatively connected ground again. This time there was no problem. So I started the motor and noticed no water from the telltale. Checked the outlet, all clear. Haven't checked the intake vents or the water pump yet. I'm worried now that I ran it the whole trip without noticing the telltale wasn't flowing.

I'm working on the assumption that I have a dead short (i.e. the motor chassis is live and looking for a ground) when the motor is tilted and I haven't ruled out the possibility that that short may have caused other damage. Could that have taken out the thermostat causing the water not to flow?

Any advice would be greatly appreciated.

Cheers,

Sean

[ericcs]

the thermostat won't have anything to do with the electrical issue. start the motor on the muffs, and if the telltale still shows no water, stick a bit of wire up the hose, in case there is a salt build up. Or you can pull the telltale hose of the nipple on the powerhead, hopefully just a blockage!

would have thought the main fuse would have blown if there was a short somewhere. i'm guessing it has electric tilt and trim?

[Noelm]

You need to back track, first thing, disconnect the electrical work you just did, reconnect battery, is the short still evident? if no, check all the wiring from the battery all the way to your switch panel and accessories, is the electrical system suitably fused? the tell tale not working doesn't mean the water pump is not working, probably unrelated to anything you have just done, are you sure it was working before?

[mawhins]

The tell tale was definitely working after the first trip when I flushed at home. I've removed the hose from the engine casing to the tell tale outlet and checked it's clear.

Will follow your advice and remove all wiring changes and check for the short.

Regarding the fuse blowing, I don't see any fuse on or near the battery. Should there be a fuse on the engine circuit? There is a 30amp fuse on a wire that must be 3mm thick at the console that I assumed was for the bilge pump. Perhaps I need to properly identify that cable.

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[mawhins]

Yeah I thought the thermostat might be a symptom not cause. Yes it has electric start, trim and tilt.

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[Noelm]

How about this for a wild stab in the dark guess, the water pump failed, engine over heated, melted a cable to the block, but motor spluttered on, you get home, get ready for a flush and the cable is well and truly grounded and smokes! no idea if that happened, and it's pretty unlikely, the strange part, and it could be a clue, is the bonding wires getting hot, that indicates the motor isn't properly grounded by the negative back to the battery, but rather somehow by the motor bolts at the transom.

[stevej]

Did you rewire the boat fully yourself ?
Havnt earthed to the hulk have you ?

[mawhins]

How about this for a wild stab in the dark guess, the water pump failed, engine over heated, melted a cable to the block, but motor spluttered on, you get home, get ready for a flush and the cable is well and truly grounded and smokes! no idea if that happened, and it's pretty unlikely, the strange part, and it could be a clue, is the bonding wires getting hot, that indicates the motor isn't properly grounded by the negative back to the battery, but rather somehow by the motor bolts at the transom.I was thinking along the same lines that maybe when the motor is tilted, because the way the cables have been run puts them under tension and because I'm using a wing nut on the battery terminal the ground is compromised forcing it to look elsewhere for ground.

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[mawhins]

Did you rewire the boat fully yourself ?
Havnt earthed to the hulk have you ?I haven't totally rewired, but I wouldn't rule out having accidentally earthed the hull with what I did do. I'm going to wind everything back and try tracing the problem from there

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[Noelm]

To rewire a boat it's best to rip everything out and start from scratch, patching and working with old wiring is asking for trouble.

[mawhins]

To rewire a boat it's best to rip everything out and start from scratch, patching and working with old wiring is asking for trouble.Yeah good advice, makes sense.

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[mawhins]

Got home from work, put the motor in a bucket of water well over the intake and bingo tell tale working. Not super strong but working.

Pulled the switch panel apart disconnected all light etc. and traced the wiring and worked out that the heavy wire with the 30amp fuse is connected to the battery via the main motor positive lead. I didn't have it connected to anything and it was under the switch panel unshielded. Not smart. I'm thinking maybe that was making contact with the hull. Would that cause the smoke on the wire?

If that is the main fuse and it wasn't connected to anything that would explain why no fuse blew. Should the main fuse be setup like that, up at the console?

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[Fed]

Covering the intake ports is not enough, you really should have the water level up near the exposed part of the shift rod. The pump should be covered and it's near enough to where the gear case joins to the mid section.

Pictures or an exact description of which wires got hot, I can only imagine there would be one single ground wire running between the engine block & the yoke?

[tunaticer]

Raise the motor fully and trace the smokey wire to a bare terminal and check continuity to the hull, lower it and repeat the test. There should be no continuity to the hull.
If you do get a reading there is cable damage being activated by raise and lowering. Find the problem and rectify.

If your tell tale is not strong fit a new impellor and or housing if neccessary. $30 is lots cheaper than $1000 plus and you will sleep much better.

[Cox76y]

I have the same engine. I believe it is normal for the tell tale to appear to be weak when compared to other brands...