I have a custom woodend boat with a Perkins deisel engine in it. The problem is with starting the boat. When I turn the key the engin barely turns over. It makes a revolution and then stops as if the battery was weak. I tested all the batteries and they are fine. I also tested the starter. It is fine. The interesting thing is that when you twist the key to accessories everyting is normal. When you twist the key to the start position the ground wire gets so hot that it will burn you. It does so in a matter of seconds. What in the world is the problem? I guess it must be the ground, but I don't know how to fix it.