change the oil pump on my 1500 5.9 dodge ram and still is at 40 porcent why

and which is that you are saying

40% or 40 psi

I am assuming that "40 percent) is actually 40 psi. I was taught that 1 pound of pressure for every 100 rpm was acceptable for a stock engine. My 1999 Dodge Ram with a 5.9 averages around 40-50 psi @ 1800 rpm.it has 278,000 miles on it.

How do i change the oil pump on my 2003 dodge ram 1500 4.7 hemi