Expert: Brad Sears - 4/17/2009

Question
QUESTION: Brad, The rear wiring harness on my1973 MGB is getting hot and smoking whenI turn the ingition on. I'm not sure if you are familar with this car but standing at the back of the car and on the right side/passenger starting at the ground the wires are getting  hot and the ground wire is smoking. I connected an indenpendent switch on my fuel pump so I can turn it off inside the car and those wires are hot too. The turn signals and all the lights work at the back of the car but I can't figure out why this is happening.  Any help or direction will be greatly appreciated.

Thanks,

Mike

ANSWER: Do the wires get hot when the switch that you installed for the fuel pump is off? Let me know.

---------- FOLLOW-UP ----------

QUESTION: Brad,
Thanks for the quick response. With the switch off the wires still get hot.  I also unplugged the wires from the fuel pump and they still got hot. It's crazy.

Thanks for your help

Mike

Answer
Mike, you are going to need to do some 007 type work on the machine. It is time for a visual inspection of the wire harness to be sure that it is not crimped or that some one has not tied an auxullary circuit into it. You might also check to see if there is a defective fuel pump relay. Also the presence of heat in the wiring can be used as a diagnostic tool by getting the wire a little warm and then following the warm wire to the units that are creating the heat. But be carefull and don't set fire to the car. I usually do this tricj with the nuts on the battery cable already loose so that I can snatch the battery cable off in a hurry if I need to. The one thing that disturbs me is that a fuse should have blown before wires smoke. That leads me to believe that there are some unautherized connections somewhere.
Brad
Something was trying to get out of the back of my head when I wrote the answer. Near the fuel pump on your car there is a capacitor (condensor). If that has shorted it could be the problem.