Folks, I really appreciate your input and advice! Here's where I am after a complete rebuild of my 2004.5 5.9:

Issue - little or no oil pressure 12psi @1200rpm) on my rebuilt 2004.5 Cummins 5.9

What I've done to date (after rebuild):
1. replaced oil pump, suction tube, oil cooler & gaskets
2. verified that I have oil flow (removed filter and oil flowed into bucket)
3. checked oil and it is getting darker so it is circulating but little to no pressure

This weekend I am going to pull it out again and looking for any advice on what I should look at/check for, etc. Need to get this back on the road asap!

 

Check the pressure relief valve by the oil filter google it!

 

Thanks, I pulled it out, cleaned the spring and valve oiled and replaced. Anything else I should look at with it?

 

Put it back in nut it's usually the spring that goes bad I said nut LOL Drinking game losing or winning!!