Writeup on the HPFP failure and its cause?

Generally speaking, I know what happens - metal fragments score/contaminate anything they touch. Seems to be tied to fuel lubricity deficits. But I've searched and haven't seen a HPFP failure 101 writeup. Anybody have a link? Thanks guys.

Ok, now I've found an old thread titled CR engine HPFP analysis. And wow, I see that VW engineered an overly complex HPFP with a cam and roller that want to annihilate each other if not adequately lubricated. I've been studying the thread for 45 mins and am only 7 pages in.

The problem is not that the CP4 injector pump is "overly complex". The problem is that it is oversimplified (in the interest of making it cheaper) to the extent that certain potential long-term wear and/or failure modes are not addressed by the design.

Agreed that overly complex may not be the right description. Designed to be unduly stressed, perhaps? For example, two cam lobes really necessary? Meaning 4000 piston strokes per min at 2000 crank rpm, with no steel piston sleeve? And that roller is turning RPMs at a multiple of the cam! Has there been a determination whether/when/why the piston is rotating in the cylinder?