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Help! My wiring caught fire and I don't know why!

S

Sergeant_M

New member
Good evening all,

I recently inherited a 91 Forester 16ft fishing boat with an Evinrude 50hp VRO2 (E50TLESR) Motor. The boat had been in storage for 15+ years, but was still in pretty good condition. I've already serviced the lower unit (New Water Pump), lube, etc. I rebuilt the carbs, fresh plugs, went through the whole checklist in the manual. I had tested everything yesterday, the motor ran good and it was pissing water as it should. I was finally ready to launch today and was just getting the final touches together. I pushed the battery back into it's little storage area and jumped out to grab the fire extinguisher I was going to mount. I get back to the boat and there is smoke pouring out of the entire length of the remote control wiring harness. I quickly pulled the battery out and disconnected the positive side. As I was disconnecting the positive lead the starter kicked for about a second. It appears that the Negative and Kill Switch Wires have completely melted. Initially I thought that there might have been a short between the Neg and Kill, but looking at a wiring diagram those wires are of the same polarity. None of the other Positive wires seem to be damaged. I do not read continuity between the negative wires and any of the other wires. The starter motor currently reads 0 Ohms resistance from the positive lead to the mounting screws. The key was not in the ignition, so there should not have been any voltage to the starter. I thought that maybe my cheaper klein meter was not sensitive enough to detect minor impedance so I also confirmed with my Fluke and the resistance is indeed zero. There are no obvious signs of burning after the harness connector going into the motor. I put my meter on just about everything I could think of to find a short circuit somewhere, but I am not familiar enough with this boat to know for sure. I am trying to figure out what caused this problem before I install a new $300 harness just so that it can burn up again. I am completely stumped at this point. If anyone has some input it would be greatly appreciated. I was having issues uploading images directly to the forum so I uploaded them to imgur here, https://imgur.com/a/XrwpWf7

Thanks in advance!
 
Welcome. A short at either end could cause this. Power getting to a ground. Was it right at the battery, when you pushed it back? Hope that no power got into the black/yellow stop wire.....or your power pack is toasted too. The starter activated because power got to the wire that feeds/triggers the solenoid. My guess is the ignition switch itself.....these are often exposed to the elements which of course cause oxidation and continuity where there shouldn't be. If ground shorted to a hot wire under the motor cowling, you would likely see visible damage there.....look closely at all wiring around the powerhead. If harness is repairable....use solder and shrink wrap. Replace only ignition switch. You can check for spark at plugs right away..... before you do anything else. Just leave harness unplugged and spin motor using a jumper hot wire to the small trigger post on the starter solenoid. Have spark plugs out and check that spark jumps 7/16" using a #2 Phillips, pushed into plug boot, then held approx. 1/2" from a motor metal surface.....like a head bolt. Likely need a helper. Make sure they are only touching the screwdriver handle.....or they might never want to help you again.
 
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timguy said:
Welcome. A short at either end could cause this. Power getting to a ground. Was it right at the battery, when you pushed it back? Hope that no power got into the black/yellow stop wire.....or your power pack is toasted too. The starter activated because power got to the wire that feeds/triggers the solenoid. My guess is the ignition switch itself.....these are often exposed to the elements which of course cause oxidation and continuity where there shouldn't be. If ground shorted to a hot wire under the motor cowling, you would likely see visible damage there.....look closely at all wiring around the powerhead. If harness is repairable....use solder and shrink wrap. Replace only ignition switch. You can check for spark at plugs right away..... before you do anything else. Just leave harness unplugged and spin motor using a jumper hot wire to the small trigger post on the starter solenoid. Have spark plugs out and check that spark jumps 7/16" using a #2 Phillips, pushed into plug boot, then held approx. 1/2" from a motor metal surface.....like a head bolt. Likely need a helper. Make sure they are only touching the screwdriver handle.....or they might never want to help you again.
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Am I checking spark to see if the power pack is fried too? I am honestly looking for the origin of the issue. If I need to replace the starter and the power pack then so be it, but I can't trust the reliability of the boat until I determine where the fault originated. I am fairly certain that the fault did not originate from the battery itself. I did bump the remote control unit and hear the trim move for a half second before I left the boat for a minute or so, before I returned to a wire fire.
 
See....now you learned your lesson, should have gone back for a beer, not a fire extinguisher........Seriously, this is no laughing matter, however. You can order a new harness, repair your own, or used one. Try Tim's Outboard in Hackensack MN @ 218 682 2331, Theresa, Mike, or Dan. They might help you....ship next day. I really don't trust your ignition switch. If power and ground happen to short together somewhere, heat will build anywhere in between, right? So since there is no battery in your control center (remote), then the origin of the short must have been there......why? It has a small gauge wire coming to it from the battery.....and a small gauge wire going to ground, eh? Those are the wires that melted....might have just been the ground, but if it was the hot wire.....and it melted to the kill wire....you will have what is called...."sparknomore".....so get out the debit card, Lieutenant....you just gained rank.....it's kinda like an "inheritance tax".......welcome to boating, sir.
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timguy said:
See....now you learned your lesson, should have gone back for a beer, not a fire extinguisher........Seriously, this is no laughing matter, however. You can order a new harness, repair your own, or used one. Try Tim's Outboard in Hackensack MN @ 218 682 2331, Theresa, Mike, or Dan. They might help you....ship next day. I really don't trust your ignition switch. If power and ground happen to short together somewhere, heat will build anywhere in between, right? So since there is no battery in your control center (remote), then the origin of the short must have been there......why? It has a small gauge wire coming to it from the battery.....and a small gauge wire going to ground, eh? Those are the wires that melted....might have just been the ground, but if it was the hot wire.....and it melted to the kill wire....you will have what is called...."sparknomore".....so get out the debit card, Lieutenant....you just gained rank.....it's kinda like an "inheritance tax".......welcome to boating, sir.
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Ha! Thank you! You made me actually laugh out loud! I have no choice but to also get a new ignition switch as well. Thanks for the advice!
 
Check the area you pushed battery back into...positive post could have touched hull or a exposed wire like a anchor light wire
 
faztbullet said:
Check the area you pushed battery back into...positive post could have touched hull or a exposed wire like a anchor light wire
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Ok, so that appears to be exactly what happened. When the battery was pushed too far back it came into contact with the hull. The lowest resistance path to the Neg terminal appears to have been through the remote control. With that mystery solved I ordered a new harness. I ran the engine so I know that my power pack and starter are still good. I protected the POS terminal on the battery, but I also intend to install something back there to prevent the battery from being able to slide too far aft. What are your thoughts on mechanically bonding to the hull an additional NEG wire of lower resistance (larger gauge and closer location) to act as my fault wire if this condition were to happen again? The Negative wire for my accessories is not bonded to the boat, which is good, because I don't want to lose my lights if this condition were to happen again on the water.
 
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