Bad fuel pump or pressure regulator shims

[Ameer Antar]

I'm trying to figure out why I'm getting a low fuel system pressure on my 5000 turbo. Right now, I'm getting 83 psi for system pressure which is just shy of the minimum value. Warm control pressure is on the high side at about 55 psi. I'm thinking it's probably better to have the system pressure on the high side as well to balance the control pressure.
 
So how can I be sure it's the fuel pump and not an issue with the pressure regulator? I checked the fuel delivery rate and I got about 700 mL in 30 seconds. This was at 10.5V at fuel pump connector. It's a bit higher than the minimum spec in the Bentley, but I'm not sure if the Bentley chart applies to all fuel pumps or just non-turbo pumps. The pump almost looks like the original, so I'm almost leaning toward replacing it. Does anyone know if the delivery rate is supposed to be higher on turbo fuel pumps vs. NA pumps?
 
The only other thing I could think of is pressure regulator in the fuel distributor needs to be shimmed. I actually took it out and cleaned the regulator. It was very clean, and I noticed there are no shims. This is supposed to be a rebuilt fuel distributor, so I'm a little surprised the pressure would be off. Does anyone know where to get these pressure regulator shims?
Any advice is much appreciated.
 
-Ameer