After the brand new battery randomly going dead in my truck, today I have a chance to start looking for why it does. Disconnected the positive cable from the post and hooked up the multi-meter and the relay near the airbox clicked and the fuel pump started priming. Is this normal or could it be the cause?

Truck is a 1989 F150 5.0

 

sounds like you grounded pin #6 and it primed your pump.