Truck is not at my store yet. It broke down over 3 hours away while on the highway pulling a trailer. I'm waiting for it to be transported here.
My comment has to do with the basis of the diagnosis my customer received on his truck, irrespective of anything you have posted here. Additionally, from other sources outside this forum, more people are starting to look towards the lift pump as the cause of the CP4 failure. The fact that the CP4 goes out isn't being disputed, it's what's leading up to that that is. Furthermore, the CP4 was redesigned to address the asymmetrical lobe design and that has not stopped the failures (the truck that just blew up is running the new style pump) which would suggest that the cause of the failure is not directly related to the pump itself.
https://www.duramaxforum.com/threads...arison.994717/
Here's a link to a conversation that goes into what I'm referring to. The suggestion is that the lift pump is over pressurizing the fuel supply gears. Whether or not this is the case on the CP4 failures is presently unknown, but based on pump design differences between the 3 and 4, it would make sense that this is a solid starting point to look at.