Thanks for reply. The trouble I have with testing this design is the pressure sensor is on the rail. The rail has one feed from the pump but no return. So the pump returns excess fuel. Dead heading the pump would isolate the sensor.
In the end I took a closer look at the pressure sensor output whilst the engine ran on brake cleaner and noticed a small increase in pressure. As I was still getting a returning code for fuel volume circuit I once again checked my testing to prove beyond doubt the wiring was sound and load tested the loom with my trusty big bulb.
Bosch ESi information does not make it clear if the fuel volume solenoid is energised to open or close. I tested the solenoid with the airline and established that when energised the solenoid passes fuel. Finally I realised that although the pump was sucking and the low pressure side was providing fuel the pump must be starved of fuel on the high pressure side if the volume solenoid was not energised on cranking.
Next I briefly took ECU pin M4 on the centre terminal block to ground whilst cranking and the engine started immediately. The ECU is presently away for test and hopefully repair. I will post some waveforms of the expected patterns soon.