Short in a 5 year old wiring harness?

JuiceClark · Post by **JuiceClark** » Wed Aug 05, 2009 3:13 pm

So, I'm running along the ICW on Sunday. Nice afternoon, got her at 3000 rpm and about 19mph. All of a sudden the starboard engine just totally quits. No cough, no deceleration....just off completely. When that happens it almost feels like you hit something because it slows so fast.

Anyway, I checked a couple things and saw there was no power at all to any of the switches or gauges to that engine. So, I knew that engine's breaker must have tripped. I dropped anchor and went down and moved the sofa and lifted the hatch. When I pressed the red button to reset the engines breaker, the harness went SNAP SNAP SNAP and I saw sparks inside the black, electrical tape that's wrapped around and around the wires of the harness. The breaker blew again right away and, at least, I'm smart enough not to press it again.

So,
a.) how the hell can wires, all wrapped up, just short like that?
b.) I'm glad the spark didn't ignite some fuel fumes being just 10 inches from the carb.!
c.) it's always electrical problems! I can't recall an engine or other mechanical device ever letting me down when running. It's always some stupid wire - even on this boat that I completely re-wired and overwired.

Stripermann2 · Post by **Stripermann2** » Wed Aug 05, 2009 3:46 pm

Don't ya just love boats!

The vibration in a boat can rub wires through their insulation, inside the wrap of tape or conduit, you may not discover, until it's too late. Probably a powerlead shorting to a ground or metal component on the engine, bracket, etc...

Keep it simple, start with what you know is wrong and work from there. You most likely will have it fixed in no time.

randyp · Post by **randyp** » Wed Aug 05, 2009 3:47 pm

and I saw sparks inside the black, electrical tape that's wrapped around and around the wires of the harness.

Juice....did you unwrap that electrical tape where the short seems to be happening? Could be exposed wires touching - who knows how or why, but that would be my first try.

prowlersfish · Post by **prowlersfish** » Wed Aug 05, 2009 5:36 pm

Look for a wire in the harness rubbed thru , if it lookes ok trace the wire and find out what it goes to and check that part for a short .

rossjo · Post by **rossjo** » Thu Aug 06, 2009 11:54 am

A short can heat up wire (could they be under-size as well?) - and then the insulation melts, which shorts the wires in the harness... tough to tell - is it a factory Mercruiser harness? Luckily you're home safe!

guglielmo6160 · Post by **guglielmo6160** » Fri Aug 07, 2009 2:02 am

as a mechanic, I can say,,, sh'''''t happens, I see stuff like that ALL the time,, if things didnt happen, there would be no technicians, mechanics etc,, sometimes I am very surprised