Using the Mark1 fuel rail to fix my squeaking pump was a non-starter. The fixing bolts were set much higher than on my Mark2.5 rail. I could either do some welding on the Mark1 or modify the Mark2.5 which was what I did. Although not fitted with a return it did have a device to reduce the pulsing effect from the pump. In this photo I have removed the rail and injectors.
Here you can see the device for reducing the pulsing fuel, it does not have any connections and just attaches to the rail. There is another one of these devices in-line with the fuel in the engine bay
Now with a new fitting that gives me the output to make this a return system
Not the most elegant bit of engineering but just right for this job
Now I have a return I can fit the fuel pressure regulator, the little blue thing. I fitted a pressure guage and set the pressure at just under two bar. Initial tests look good, the pesky squeak has gone, hopefully I will get a run in this weekend and see how it performs.
After running the car for a few hundred miles I can confirm this modification has been a complete success. I finally set the pressure to about 38psi and the engine runs great. The squeak is history and the eratic tick-over has gone as well. I have added this to my Mk2.5 notes section as this will need to be done to all builds where a non-return system was on the donor.