I think they are just low from all this cranking.

They are the AGM from advanced. A few weeks old. I'll take them out and drive them over to advanced and have them tested/ charged if I have to.

Got it started!
It is idling great in the driveway for a good half hour.

I went to reverse out, put it in drive and the engine cut out.

Batteries are at 8.6 and I'm getting just clicks when I crank.

Also when i jump it the voltage didn't change.

Pulled the batteries and took them to advanced. One tested "bad cell". The other needed to be charged.

Would this cause the truck to cut out like it did?

Low voltage can ruin your FICM. I believe trying to crank below 10.8v will cause issues.

I'm not seeing that code.

Got the new batteries on and it's cracking now. Icp is too low to fire. How long does it take to purge. I had the truck running for a half hour earlier. Was that not long enough?

Keep purging, you may still have air in the HPO system. Look up Diesel Tech Ron’s instructional videos.

Thanks. I'll keep at it.

I'm getting there. At ever crank interval I get 20-30 psi higher on the icp. Nearly there!

Keep those batteries up and give your starter te to cool off between cycles. It took mine about 10 cycles to purge air after HPOP, HPO update and injector replacement.

That's exactly what I'm doing.

I'm good 15 cranks in and only building 320 at the icp

Sounds like you might have a HPO leak.

To the OP...did you do all this? If you replaced all these HPO parts and can’t build ICP over 320psi I would think you have a big high pressure oil leak somewhere. A smaller leak will allow ICP to build enough to run sometimes but a big leak won’t allow you to build enough to even start. Those nipple cups and seals are hell. I replaced mine with HHC cups and new o-rings. I tried rebuilding all my injectors but had a bunch of wear in the spool valve ports even wuth new spool valves I had 3-4 injectors leaking. I ended up with 8 new injectors and wasted about $1200 on injector rebuild parts.

I did all of that. All new injector o rings including the top. New copper washers on all. New IPR. Checked stand pipe and dummy plugs. Replaced all nipple seals. Put it back all back together and air tested before i put the valve covers back on. Had no air leaks.

3 cranks later I'm at 385.

It took me this long for it to fire this morning.