Isx wont start

[Toddmsc]

I have an isx cm2350.
It had coolant in the fuel. Bypassed tank heaters and confirmed injector cups or cracked head. Being around many of these, the machine shop, and from my personal experience...I have never seen a sohc head crack yet. The dual cams I've seen plenty of.

Anyways, truck has a b.s warranty on it so and I have enough on my plate to deal with so I figured with, I'll have them deal with it. Drove it to shop no codes, not running rough, nothing out of the normal operation of the truck. They bring it in call me say its head or cups warranty doesnt cover either. So I told him ok fine put it back together I'll do the work myself. Only reason I brought it there was the hope of warranty footing the bill. He calls me later and says well its together but doesnt run send a tow truck. At this point I'm confused to why I gave them a running truck with no codes and I get one back that doesnt run. They say bc they used the old injector o rings and most likely they are leaking causing a low pressure no start problem. So i got it towed home.

I had finally got some time and took back apart. Pressure tested it and 1 4 5 6 all leaked. Cummins has a tsb on leaking sleeves and they make a retaining ring kit to solve the problem. Bought it, did it, and fixed the problem. This pressure test none of them leaked anymore. Sweet! So I think.....

Put new o rings on the delivery tubes and new orings on injectors. Put all together. Primed it made sure there were no air bubbles. Made sure at the primer pump, the in side of the high pressure pump and at the filter housing. Still no fire. I do have the notorious fuel lower than commander and the injector metering rail one low pressure codes. The primer pump is doing its job.

What would have made the high pressure go all of a sudden? Can I get away with a new head on the pump?

I do not have insite still waiting for it to come in cant take not having it anymore. Would have been nice to see rail pressure before spending the 1500 on a fuel pump head.

Thoughts guys?