Truck is a 99' Ford F350 with a 7.3 diesel. Came into my shop with extended crank issue, once it starts it runs perfect. No codes, performed diagnostic procedures tested each glow plugs for ohms, and found 6 of them bad. Replaced the glow plugs, replaced relay as well per customer request. Still have the extended crank issue. I know the vehicle needs oil at 450+ psi to start. I hooked up the scan tool and monitor the ipr and icp on crank, ipr reaches 450+ psi and starts up. Turn the key off and ipr goes down to 0, I just want to know if the ipr is supposed to maintain pressure with the key off or key on engine off.