Fuel pressure!!
 

Hi all

Any ideas what the fuel pressure should be on the M275 65 AMG engine in a W221? WIS does not have this information anywhere (frustrating)

The M275 training document has it, it says 3.8 bar constant, and if it drops the fuel pressure, the control module increases voltage to the pump. I am taking this with a pinch of salt though, as I know other AMG's run a higher pressure (5 bar +)

Is this right?

But what kind of fuel system is in these other AMG's engines?
Fuel loop with pressure regulator (which maintains constant difference between intake and fuel pressure in rail), or like the M275, which delivers
3.8 regardless of pressure in intake (and no return to the tank from fuel rail)?
I do not know the answer, but from the M285 document, it seems that it also uses 3.8 bar.

br,
syljua

Did you find an answer to this? Not much accurate data to be found online so we measured a few locally. My 05 CL65 has 55psi at idle. A different CL65 has 55psi. A CL600 with updated 5bar controller has 75psi.

I measured mine at 75psi at idle. 221 has a slightly different fuel pressure regulator design but I belive its probably set at 5 bar.