Fuel/Differential Pressure

Can some shed some light on what is going on here? Problems are 1: FPR will not adjust the base pressure (tried 2 different regulators) .... can only adjust pressure by increasing or decreasing the Pump DC. 2: Differential is high

I have replaced the Filter Cartridge and tried different fuel pumps.

The car has been sitting for a month, prior to that the fuel pressure situation was fine.

Have attached my Tune file and a log.

Any help would be appreciated.

Note: Connecting the vacuum source does not change the fuel pressure.

Return line blocked maybe? Disconnect the return line and run it to a bucket or something so you can see whats going on.