high rpm + high boost = stumble

[Phil Payne]

> This may be totally off-the-wall anecdotal experience, but in my
200q20v,
> for about the last six months prior to the fuel pump failing
completely, I
> was experiencing occasional stumble under WOT acceleration when I
got into
> the 5-6k rpm range.  This would be a third gear circumstance mainly,
so I'd
> be at 1.6-1.7 bar in a stock 20v.  With no other change than the new
pump,
> the engine spins up as happily as it ever did for me.

I had this on the Bus.  It turned out to be (essentially) cavitation.
The gauze screen was blocked - see the 'tank lining' TSB - and the
pump was sucking so hard at the back of the screen that the fuel was
boiling at ambient temperature.  In my case, a left curve made the
problem worse - didn't have to be a hard corner.  I removed the screen
as per Audi, and the problem went away.

--
  Phil Payne
  http://www.isham-research.com/quattro
  +44 7785 302 803
  +49 173 6242039