Seahunter, your problem sounds almost like the issue I had recently (see my post "CAT 3126 No Start" from a few days ago). I never did determine the exact cause; I had a mobile mechanic ready to leave his shop to come to me when my engine started. The only thing I did differently was to leave my battery disconnect ON overnight.
I had tried all the things you tried and nothing helped. Then, after leaving the chassis battery disconnect on overnight, I gave it one more try. Started right up. I've since driven the coach and it continued to start and run fine.
There should be a fuse (about 20 amp?) in one of the wires connected at the batteries. Since you saw sparks, you may have blown that fuse. Please recheck all your connections, including any inline fuse, and see if it will start.
Don't be offended by posts that have nothing to do with your problem. Many people will offer advice based on their experience, which may be with a different engine and doesn't apply to you at all. Just separate the wheat from the chaff, and let the chaff blow away.
