Posting to update: i had a partial success. i installed a lift pump and the van drives much smoother on WVO now (although i still think i may have damaged the stock pump), but the van is still limited to 2k revs (on WVO and for a few days on diesel after driving on WVO).
So now i'm assuming its mainly an electronic issue. i will look for someone with a Sprinter code reader, but my project has hit a big bump and i'm completely out of money, and expect to be so for the next month or 2, until our Kindess Auction builds steam.
Can anyone suggest a fix, to stop the engine going into what i presume is limp home mode? or to change the timing, which i think related to, or the cause of the issue?
Thanks very much for youradvice and support! i'm in Germany and heading into Poland ..just very slowly :P
Andy
Focallocal - Focallocal