The last few weeks of fuel system discussion has what's left of head begging for mercy. I have sorted out a couple of things. Fer instance the FPR and CPR although similar in function (regulating pressure) the where and why for are substantially different . The location is even within a few inches relative to installlation.

I have pretty much answered my own question about CPR resistance as I fell over the information in Bentley's.

The check valve ? Is it in the hose between the main pump and the accumulator or is it in the pump itself ? Is the answer dependent re, turbo or non turbo ?

Fuel pump capacity and pressure. I have seen a variety of opinion re. fuel pump adequacy to produce adequate pressure for various engines.

I thought except for extreme variations the accumulator and CPR/FPR would handle the work of maintaining the correct fuel pressure for the system in question

Next the relay melee