Some of the more complex piston turbocharged fuel systems have altitude limitations associated with partial fuel system failure. If one of the two (or three) pumps that supplies an engine fails, it may not have enough pressure to go higher than about 15,000 ft or so, effectively starving it for fuel above that. The engine will be fine below the altitude where the remaining fuel pressure is enough. Obviously it something to do with turbo boost, but I am not sure what exactly.
Last edited by Cubdriver; 02-25-2013 at 08:52 AM.