Normal rail fuel pressure? Code P00C6

[dragstang86]

What is the normal fuel rail pressure for a 2017 Sierra with a 6.2?  I am chasing a no start condition along with a P00C6 - Fuel Rail Pressure Too Low - Engine Cranking Bank 1.   I'm not sure what normal is. While checking it with key on and cranking, I have seen it anywhere from 520 - 600 kpa which is like 75-85 psi.  What should it be?

[newdude]

On 6/22/2022 at 10:06 AM, dragstang86 said:

What is the normal fuel rail pressure for a 2017 Sierra with a 6.2?  I am chasing a no start condition along with a P00C6 - Fuel Rail Pressure Too Low - Engine Cranking Bank 1.   I'm not sure what normal is. While checking it with key on and cranking, I have seen it anywhere from 520 - 600 kpa which is like 75-85 psi.  What should it be?

 

 

So key on engine off and not cranking, are you are getting 75-85psi?  You need to be able to read your high side fuel pressure.  Sounds like you are only reading the low side.  

 

These engines are direct injected engines, so the fuel system has two sides to it.  The low side and the high side.  Low side is from the tank to the input on the high pressure fuel pump.  The high side is the high pressure pump to the injectors so HPFP, fuel rails and injectors.  

 

Rail pressure on these DI engines is MUCH higher than 75psi.  Engine on idle, it should be making 500-700psi, up to 2500psi at WOT.  Cranking psi about 300-400psi.  It is quite likely that your high pressure fuel pump is no good and needs to be replaced.

 

I would get a hold of a scanner that can read the fuel high pressure sensor data and see what the pump is making during cranking.  

 

There is one other possibility for this code, and its a possible issue where the cam position actuator solenoid valve could be intermittently sticking, but this ones requires some extra diag work. 

Edited June 27, 2022 by newdude