Have you used up all the fuel in the tank?
I've done this before and thought it was something else.
This is only a silly question if the reported running rich condition is correct.

If fuel pressure regulator isn't losing fuel out of vacuum port.
You can check fuel supply by disconnecting the fuel return to tank hose , put end of hose into a container , make fuel pump run, if you get a strong flow of fuel returning to fuel tank fuel supply is likely to be good.
You don't need a gauge for that test.

OK if the arrow was pointing towards the filter and away from pump that is supply pipe , plus supply pipe always has filter.

Do the is fuel flowing freely from the pressure regulator back to tank test.

No fuel in returning line next to fuel rail when activating fuel pump

Your tank is empty

Mystery solved. Returning line clip was not tightened correctly. Uh...
Thanks a lot Jack for your patience.

No problem. This sort of thing can happen to any one.
Please post picture of clip that caused problem and confirm which pipe it was on.

Will do when I get back home, for future reference, there might be people with the same issue.

Here it is, fuel line that was not torque properly, allowing air to come in, which produced rich condition in the end.