Machine serial number? This will help to determine the exact fuel system on the engine.
Why was the HPCR pump replaced?
Are you having rail pressure mismatch codes? Any other codes? What symptoms are you experiencing?
What is the fuel pressure reading in the monitor first thing in the morning with the key on, engine off?
There is no published spec for High Pressure Common Rail fuel pressures. On a "J", which has an older HPCR system (if your serial is over 159987), I would think a no load fast idle reading would be in the 12,000-15,000 range and higher when loaded, going maybe as high as 18,000-25,000 at full load.