Just an update,
I checked the wires at the 6 way plug at the accelerator and got 5v at one and 3.5v at another. The other 4 were 0v.
Having looked at other bosch ecu pinouts, It seems there should be 2 number 5v supplies, 2 earths and 2 signal.
Today I will trace the 6 wires back to the ecu.
Also, at the fuel pressure sensor, the three wires at the connector give me 5v, 3.6v and 0v.
But when they are plugged in and I pin into the wires to test the voltages, the 5v has dropped to almost 0v, showing 0.05v.
This is very confusing and any comments would be appreciated. This happens with my spare sensor also and neither of the sensors show any internal short.