Replaced Pump Two Months Ago .... Truck Ran Fine Until Last Night Truck Started Right Up Went To The Store Then Acted Like It Was Out Of Gas ... So As Usual I Grabbed A Can Put 5 Gallons I No Start Cranks Fine So Today I Checked The Relay Its Fine. Got Under The Truck Disconnected Fuel Pump 4 Pin Connector Both Black Wires Were Off The Charts As Far As Continuity Goes So Im Losing Ground Some Where ...But Im Only Getting 5V At The Pump. Im Thinking The Problem Could Be The Splice That Came With My First Pump A Couple Years Ago, Yes I Should Have Checked It Before Replacing The Pump But The Pump Was Covered BY Warranty N Ran Fine So Im Stumped Until I Trace The Harness Any Help Will Be Greatly Appreciated .... Im Also Going To Add An Addtl Ground To Be Safe Thanks In Advance!!!

 

Think you found the problem if there is only 5V at the fuel pump...it is not going to work at that voltage. Others have had problems with the ground connection for the fuel pump so good idea to improve this. Also suggest reading over the many threads on fuel pump wiring as there is a connector that fails.
Lastly hope that a Delco fuel pump was used as off-brands seem to have a short life.