Thanks for the reply guys,
Im along the same train of thought that its a regulator as it looks like the ECU is controlling it. Also when giving the regulator a little tap whilst running the fuel pressure bounces all over the place.
Im with you on the theory Lee that the hp pump shouldn't cause a high pressure issue.
Not a fix yet as my customer doesn't want to pay the dealer price but as far as I can tell its a dealer only part.
Thanks again for the help
Dave