This is how a 4cyl. Common Rail Marine Cummins system looks like, though it was interesting, and pretty simple.

 

Thats pretty much how they all are set up.Bosch owns the patent,so everyone has to use thier system.Volvo,MAN,Cummins etc.Verry little differenc in the systems.

 

just missing the injector return drain lines and it is a complete drawing

[return is needed, without it, there will be no pressure differential across the cartridge and injector can't fire. the solenoid doesn't mechanically lift the needle valve in the nozzle, pressure differential from the bypass opens it.]

in my opinion, all hpcr fuel systems should have flow limiters on the hp lines to the injectors, but i haven't seen a system yet that does