I have changed rail pressure switch on bmw 530

Hi we have a similar fault on a 2002 X5 diesel with 140k.km
scan test on 'Autologic' says > low fuel pressure in rail under starting< we have done leak off test at diesel specialist and they say it needs #4 and #2 injector renewing, the low pressure from tank is at spec at approx.3.4bar whereas the rail press at crank is only between 102bar to 140bar on 6 diff scans, where i believe it should be at around 390bar, hope this helps, we still have not fixed this yet,