car came in originally 3 or 4 weeks ago for intermittent poor running and occasionally cut out .scan showed a number of fault codes including some for high fuel pressure signals.

There was quite a lot of air circulating in the system so we changed the fuel filter and ensured an air tight seal,cleared codes and let him use the car .he brought it back 3 weeks later saying it had been ok for a while but the last day or so the symptons returned.

We changed the whole filter housing as at times air could be seen in the clear pipes after the filter mainly after a hard decel. Code for high fuel pressure was again present.access is pretty poor to connections at the fuel pressure sensor and the 2 regulating valves on the pump so gained access via the ecu pins.

Autodata don't have the wiring diagram right so had to trace individual wires back to the source at the ecu.this is where things started to go wrong.i got what i think are the correct scope patterns for the 2 regulating valves albeit individual channels. When scoping the fuel pressure sensor initially got ref voltage 0.5v idle 1.1v hard accel 3.7v but on return to idle the voltage remained at about 2.0v for about 20 secs before dropping back to 1v. Thinking i had wrong connections to the scope and to eliminate some possible hash i used the scope earth in the sensor earth (floating earth ?)shortly after this the engine stopped and wouldn't restart. fault code and live scanner data show 2000 bar pressure all the time and all the 3 terminals at the ecu for the fps show 5v, sourced another fps but doesn't work on a variable resistance as i thought.

Any info on how it works electrically and how check off the car please .if i have damaged the ecu can i source a secondhand one and fit it without coding etc.any advice gratefully received regards paul