Hi, Can anyone sparky savvy help me out?

Had a performance problem with my 99 FX for the past six months, went through everything to try n figure out what the problem was and ended up tearing my hair out, so eventually gave in and put it in the shop. 300quid lighter later and the bike runs a lot better but still not hundred percent in the mid to top end range. The issues it turns out are with a partially melted wiring harness.
The guys in the shop have sorted some of it by replacing some of the wires etc, but they dont seem to know what might of caused the overheating.
So my question is does anyone on here know what sort of things can cause a wiring loom to melt? The damage was mainly up on the left hand back end coming out of the ECU.
There was a scottoiler positioned above it by the previous owner but i removed it cos it was dripping oil on the said cables, the shop guys dont seem to think that oil would be enough to melt the casing's however.
Ive since been teaching myself electrical systems and am having a go at doing the rest myself, but im concerned that if i sort the other bits of dodgy loom out that whatever caused the loom to melt by the ECU could happen again? Where the bad loom was there was one cable that had no insulation on it at all until i spotted it and wrapped it before it went into the shop, so if a cable has no sheathing and was touching the frame could that ground the wire out and therefore cause that whole section to overheat?
Cheers

 

That will most definetely ground it out, bare wires against frame, straight short. I`d reckon the oil itself should not cause melting, BUT it does conduct electricity some, so that too is a possibility. Wiring loom meltings are usually caused by the regulator/rectifier going kablooey but it normally melts just it`s own connector and wires near there. Bad connections like twist joints, badly crimped connectors, oxidisation etc are potential spots to get hot as the contact surface is reduced there. Think of a one lane intersection in between a four lane motorway and everyone wants through first. That`s what happens there, things can get a bit hot.

Running issues may be because of a bad or partially charged battery. I`ve been told these bikes can be finicky about the batt being full and in good spec.

 

yep it would short out and melt what ever's touching it and the heat would disperse up the loom i would take the loom off the bike and unpick all the wrap and cheek every wire and make sure there's no more bare wire or meted ones just because they have change that part does not mean its not melted some where else on the loom

 

thanks for your replies, thats great ill voltage drop test the rest of the wiring loom than take it off and check the rest of it for burnt out bits and dodgy connections etc. ill also check the reg/rec.


I also just voltage drop tested the positive and ground side of the fuel pump circuits, the negative side is reading 0.01 which is right i think, but the positive side is reading 1.54, im a bit of a newbie with electrics so im assuming that this mean's that there is bad continuity in that circuit and that the voltage is 1.54 volts down? Would that then mean that if the fuel pump is not getting enough power that it wouldn't pump fuel as hard? im wondering if this is what's causing my performance problems in the higher range perhaps. I asked the garage mechanic and they said there may be a relay or something that drops the current going into the pump too n these models but im not sure about that.
Cheers