DOHC fueel pressure

[voucht]

Thank you for the replies, very useful to me.
I want to fit an adjustable fuel pressure regulator because it looks like I have too much fuel going into the combustion chambers : some fuel is apparently not burnt, I can see that to the smell, black smoke indicating a bad combustion, and to the colour of the spark plugs. I checked the ignition and everything seem to be working normally there.
If the OEM fuel pressure regulator is not functioning correctly, and there is too much pressure in the rail, can the injector inject too much fuel in the chamber? Or is the quantity of fuel injected limited by the injector size anyway, and what ever the pressure is in the rail, the same quantity of fuel is injected?
Sorry for my complete lack of knowledge when it come to this matter
Thank you very much.