NOT STARTING

[S4RR]

Hi guys,
i have a 66 plate VW polo 1.4L TDi engine CUSA. and its not starting it sat for around a year then we ran it for a couple months then one morning it didnt start now we have taken it to the diesel specialist they have changed the fuel pressure sensors the high pressure fuel pumps 3 times with new working pumps the one in it at the moment is Delphi, the low pressure fuel system has been checked and is working the ECU has been checked and is working and the engine runs when using easy start. the mechanic said its only preducing 2 bar worth off pressure, when cranking it sounds very healthy with no unwanted noise.
We cant find the issue, any advice or help would be appreciated
thanks.