Can we clarify this - no gas coming into the carb means it will not run - as against too much fuel and running rich.
If you installed a regulator and there was no gas to the carb, then you have two possible scenarios ...
1) incorrect installation.
2) defective regulator.
I was considering a third possibility - the wrong choice of regulator, but even if you chose a regulator with too high a pressure setting, it should still allow fuel to flow.
If you installed a regulator and it is running rich - please first note that excess pressure is simply one possible cause - the options are ...
1) incorrect installation
2) incorrect setting (although you seem to have this covered)
3) defective regulator
4) carburettor related issues.
Wait a minute - I had, at 5.0, no gas coming into the carb - meaning the regulator cut the fuel off when set to 5.0 - I tell you, proper punctuation does wonders for readability.
If that is what you meant - check to see if you have the regulator outlet & return lines routed correctly - as you increase the pressure setting the regulator should divert less fuel to the return and more to the outlet, assuming that the pump can supply the required pressure, and when you exceed the pump capability, it will/should send all the fuel to the outlet & none to the return.
That cut off at 5psi suggests that you have the lines reversed.