Possilbe fuel pressure issue?

Ok so i’ve done some searching and i cant find the answer im looking for. My car is running pretty rich and we thing its something fuel system related. My timing is set at 20 degrees on 91 octane gas at 3500 feet above sea level. Spark plugs are brand new, as well as the o2 sensor and fuel filter. Its pretty obvious its rich cause man the exhaust reaks and the muffler tip is covered in carbon build up. I have done a fuel pump pressure test and was given a reading of 46 psi then the needle fell down, almost immediately to about 10 psi. Is this normal with skylines? Something in the fuel system is causing to much gas to flow into the engine. Could the pressure regulator be hooped? Got any ideas?

Regulater sounds about right PSI, could be that the injectors are getting an inccorect reading from the ECU. But Id take it somewhere that knows what they are doing cuz it can always be sooo many things.

yeah… could be many things, if you’re lucky its a bad FPR.