6 volt regulator kerfuffle

[El Rat]

I seem to have recurring regulator problems. Most where caused by a 6 volt generator on steroids! However I need someone to explain this to me:
I can "jump" the generator (armature to field) and the generator makes 8+ volts quickly. In addition, it will run when the battery is disconnected...until I remove the "jumper" then it dies immediately. Why does the engine die when running thru a "suspect" regulator but not when jumped? I just don't get it! Comments appreciated, Thanks gene