I have a 2012 6.7 ram that won’t start after installing a brand new fire ring head.

[gsbrockman]

I tried bleeding the air out of the fuel rail and still no luck.
I looked up bleeding fuel rail and found out I don't even need to bleed it.

I’m no mechanic.....but even I know that a HPCR fuel system doesn’t need bleeding. Sounds like you’ve gotten “hosed” and “bled” more than once with that shop.

 

[Donnie Cresswell]

View attachment 126441

Sorry that’s the wrong code.
Here’s the right one.

 

[Donnie Cresswell]

Correct on the assumption of no need to bleed rail, however, you still need basic fuel flow supply. Do you have fuel flow to the CP3? What is your rail pressure when cranking?

I have plenty of fuel getting into the brand new CP3 I just don’t have any equipment to check rail pressure.

 

[sag2]

The P0193 could be the sensor unplugged, the sensor ground missing, the sensor signal shorted to voltage, sensor, ECM.

The P0254 could be the FCA wiring open or shorted to voltage, FCA.

I think I would unplug the pressure sensor and the FCA, clear the codes and see what comes back. Then try to start it again. The unplugged FCA will give it max pressure, but not sure on a 2012 if the rail pressure sensor is unplugged if it will substitute a fake pressure. You really need a scan tool to see what you have going on.