Hello John,
I think judging by your last four posts that you are one of those garages that makes gaining customers trust so difficult for the rest of us. It sounds like you haven't really carried out much testing,instead just using the parts shotgun method, but that could be the way that you have written your post I suppose. Were you monitoring rail pressure before you decided to replace the releif valve or the IMV? did you do a spill test or measure low pressure supply?
I agree with Dave & the others & think that you should get some training or do something else, as I am fed up with customers coming in after they have done the rounds with garages like yours, who have generally ripped them off & then they don't want to spend any more on proper testing & also moan when it is something simple that we have charged them fairly for.