I wouldn't think an internal issue with the pump could cause this since the IPR is what controls the pressure. I'm assuming at this point I damaged the IPR & need to replace it to correct this problem. I then sprayed some brake clean in while manually operating the plunger & reinstalled with no change. I removed the ipr to see if anything was stuck in it and didn't notice anything off. If I start it with the gauge in, the pressure is something like 3200 psi at idle. I removed the ICP & installed a gauge just to back that reading up. I can unplug the IPR and the system will build about 300 psi while cranking. It fires right up on a hot restart so I'm confident that part is fixed. Code 164-16 sets for ICP pressure above desired level. Truck starts & runs but now I have approximately 1500 psi of ICP at idle when desired is more like 870. Replaced all the components & reassembled enough to start the engine.

The #3 injector was replaced last year & given the mileage & difficulty to reach these, I suggested replacing the remaining 5 with new injector adapters. I didn't think this would cause a problem as the factory manual calls for a dead head test but didn't want to push my luck. When I attempted the dead head test to check pump condition, the cranking sounded slow and I stopped immediately. Long story short, the tops of the injectors where the adapters connect were worn & causing the leakage. I used a stethoscope to determine the worst of it coming from Cylinders 2 & 4 with leakage at 1 & 5 as well. With air pressure applied, I was getting a lot of noise from the oil rail. It moved closer to desired when the idle speed was raised. At the time, I was attributing this to the manner in which the test hose & fittings were installed. My thought was once the crank no start occurred, I could use the shut off valve to quickly dead head test the pump & then break in to the rail side of the system & air check while the engine was good and hot. The ICP was higher than desired with this set up installed by roughly 400-500 psi. When I performed testing prior to replacement of the parts, I set things up so I could have a gauge inline with the hose from pump to cylinder head & a shut off valve as well. Suspecting a high pressure oil system leak, I obtained the necessary fittings to air check the system. I got the engine warm & confirmed the complaint while monitoring ICP on the scanner. I suspected a leak in the high pressure oil system so I scanned it for codes & retrieved a 164-1 for ICP unable to build during cranking. I've posted a couple different things about this truck but it has yet another issue (surprise!) Customer complaint was long crank/hard start when the engine is warm. Good afternoon all and thank you for your time.

Koeo voltage ipr valve 6.0