You might check to make sure all lines are properly connected to the new unit and that it is plumbed the same way as the old one. Your power problem sounds like a venting problem, as if you aren't venting the tank
The part about disconnecting the plug not allowing your starter to engage is beyond me. I'm sure someone has a Haynes or Chilton book with a wiring diagram. Your local electrical repair shop may have a copy they would let you look at.
I had an '85 3/4 ton and my Dad has an '81, both had dual tanks. The selector valve was an expensive rascal on both trucks. We decided to get a 3/8" t-fitting and bypass the selector. Just connected both tanks together at the selector and the t goes to the fuel line to the pump. The gauge still works and I'm not aware of anything negative other than one of the lines coming off and draining both tanks.
Hope this helps you.
Last edited by cliles55; 11-14-2004 at 05:54 PM.