Gasoline has almost no lubricity. Therefore, a fuel pump for gasoline does not (can not) depend on the fuel's lubricity for lubrication.
Someone here wrote that a gasoline engine that runs out of fuel will get premature wear due to a lack of lubricity from the lack of fuel. So, even if there is very little lubricity in gasoline, I wondered if it's possibly a factor at all.
Also, that gasoline has very little lubricity supports the idea of looking at the TDI HPFP failures from an angle other than lubricity (at least briefly). The design and the fuel may be very different, but is there a commonality (or more than one) that could be the problem (at least to some degree)?
However, there is one common factor - any high pressure pump (whether it is pumping fuel or fruit cocktail) puts strain on the design and the parts. The question is about how well it is designed to handle that strain.
Yes, and part of that could be related to design commonalities, despite the differences. I know very little about fuel pumps, although I do know a bit about the chemical differences between the fuel types from my small background in Chem. I just wanted to throw this out there to see if there is anything that might be gained by looking at the problem from this angle.
If ethanol was the problem for BMW, that's interesting. Some diesel additives have alcohols like butanol in them. Power Service's 9-11 additive contains two forms of it. Could ethanol have eaten away at a chemical coating? Could pump fuel have alcohol additives that are causing problems?
