I read alot about the pumps but never read what the min. presure was . On my 98. 5 the lowest by Cummins is 10 psi. . I went to the dealer today to have them comfirm what my little 16 psi gauge said 8 psi at idle. It cost me $76 and they said it was at 13psi and every thing was fine. I went to local Cummins it tested 7 psi, I was told it was defective. I went back to dealer and asked to see the gauge as they tested 2nd time, it showed 11 psi. The gauge he used was ( zero to 100 psi ) cheap looking and had black tape around it. The gauge at Cummins was a large MAC brand (zero to 35 psi) . FYI.