P008700 fuel rail system pressure too low

[Azrel]

Hi, i would appreciate it if anyone could help me regarding this situation with the fault code P008700. I have changed numerous parts such as electric fuel pump in the back and the high fuel pressure pump and an electric fuel pump and also changed all filters but still no luck.
As soon as I do a kick down a glow plug light flashes up.I have a strange noise coming from the electric fuel pump which I just changed recently I have attached the video for any suggestions would be valuable.

Thanks