why will my 96 Ram 1500 5.9 start and run if I bang on the gas tank, but wont restart after I shut it off and let it set for awhile unless I bang on the tank again?

check the ground to the electric fuel pump~ this can be maintained by finding the OTHER end of the black battery where it attaches to the frame/ground...wirebrush that lug till shiny and wirebrush the spot from where you unbolted that from~ with restored grounding potential, the fuel pump will find the ground it needs to complete the circuit and fire up that pump~...'tis a grounding issue, my friend~

you know that an electric fuel pump stays cool with the petrol in there~ no gasoline=no cooling......BURNT...in short order...sounds to me like you are asking a cripple to haul your barbells to the attic...will shop for a brand new pump for ye~

https://www.google.com/#q=96+Ram+1500+5.9+fuel+pump&tbm=shop&spd =16219178388022967343

yes grounds....

Sounds like you need to replace your fuel pump.