Sorry for delay in reply to the inputs from you guys,but have been trying injector testing which showed no fault in any of the injectors on bench testing.

Have also tried a rail pressure relief valve on the advice of Bosch technical to no avail.

Finally had the opportunuty to test data on two similar vehicles same age,one a movano the other a master,on both vehicles the only grey area is the current draw and duty cycle of the pressure regulator which is much lower than the faulty van at 700 ma 20 % duty cycle against the faulty van at 1300 ma and 30% duty cycle.

Any idea what the cause and effect of this high current draw I would have suspected the regulator but have already fitted a new unit when initially having the fault brought to me.
I will be scoping the duty cycle and current draw of the regulator together with the rail pressure whilst driving the vehicle in the hope of shining some light on this fault in case of an incorrect corrolation between demand and actual pressure.

At present i cannot see any loss of pressure when full turbo boost takes place only this dropping out when taking vehicle up to full load.

Dont you just love this game and today my Bosch esi software up grade disc has corrupted my normally perfcetly working software.Aargh!

Come on Kevin help me out here I have rectified the spacing out of the sentencing for you now I need your expertise in the technology you clearly have available to expound to us mere mortals.Lol

Btw Vauxhall technical suggested that this is a common fault and they would replace the tank,fuel lines,rail,injectors and high pressure pump est £3/4000 I suppose thats why I work late at night and weekends.Thanks for the help so far hope I can get this right and keep what was a very good customer coming back to me for the future. Times are hard enough and it is difficult to be proactive,this is one way by taking on difficult tasks and is what seperates us from the main dealers.