Thanks. Been too long since I flew a 767 to remember much about the fuel system but trapped fuel (if that what it was) in that Boeing probably takes multiple failures of crossfeed/check valves or pumps. Don't know about any additional long range tanks in the -300 either.
Sounds like the Captain went to the cabin to check for fuel leaking from either the engine or wing to rule that out I suppose.
I think there was a 767 incident years ago crossing where the crew mishandled a fuel inbalance actually caused by an engine fuel leak.
Maybe someone could dig that incident up in the pprune records to jog our memories.
found a link to the schematic:
Fuel System :: Description (skydiving.co.uk)
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