Burnt wiring inside control panel of MEP-701A

[Smallblockfuelie]

I opened up my control panel to begin the solenoid trouble shooting guidance ETN550 gave in another post and found this when I opened the door. A few wires tied up with the bad wire, which burnt in two, are needing replaced. The larger diameter wires under the damage may just be cosmetic but I wouldn't swear to it. The wire that is destroyed connected on the bottom under the terminal with the arrow. The other end connects at the front on the left. Any suggestions on why this happened and how to proceed here?

 

[PeterD]

The first thing I do when I get this type of problem is see where those damaged wires go. Sometimes it is as simple as a nick or other failure in the insulation that leads to current flow and cascading damage. Other times it is more difficult, a case of overload causing localized heating.

However one clue is that when the remainder of the wire is good and one spot is burned then it is more likely an insulation failure--overloads typically overheat the entire wire and not just a short segment.

 

[Smallblockfuelie]

The one wire was fried nearly it's entire length. I'll try and figure out what it's for.


Do I need special wire to replace what has been damaged or is the civilian stuff I've already got suitable?

 

[Jimc]

you dont need mil-spec wire. if the whole wire is fried its a pretty good bet that a component went bad and shorted out.

 

[Smallblockfuelie]

you dont need mil-spec wire. if the whole wire is fried its a pretty good bet that a component went bad and shorted out.

Excellent, thank you. The fuel solenoid isn't working so my assumption is that's related to my wiring issue.

 

[ETN550]

Quite possibly. The fuel solenoid draws fair power. Also, the 7.5A DC circuit breaker on the front of the panel should protect the wiring. So it might be stuck closed.

Back to the wiring. First stranded wire should always be used on any vibrating equipment not solid core wire. The PVC insulated automotive wire is stranded and will work. (auto parts store) Match the gauge of the existing wire. However, I like to use THHN / THW? Its the commercial wire used in conduit. (Home Depot / Lowes) It is stranded, but not quite as finely stranded as the automotive wire. However, the jacket has that clear mylar coating like the mil wire and the temp rating is better. Lastly, marine wire available at a boating store or marinia is very finely stranded and and has fuel resistant insulation and temp rating probably okay. It is made to be used in engine rooms. It can be found tinned with solder for better corrosion resistance like the mil wire is. Good stuff.