Jetdoc,
Thank you for the further information. How do the refuel valves function physically and where are they in the main (wing) tank? I recall that they are powered open during refuelling. If they are closed and depowered in flight, presumably they are locked in position? They must also have a NRV in the out-of-tank direction only?
With such an inexplicable accident it is quite likely that two rare and non-related system failures have combined to produce the engine power loss, so bear with me if I try to eliminate all possible ways in which air might reach the tank pump inlets ( given that there must have been 2 or more system failures for that to happen)