Thanks, gents.
After further investigation, there was actually a modification carried out to the FQPU with that on-ground stuff (I think the FQPU already had access to all the data that the new logic requires: air/ground, refuelling in progress, CMC Ground Test in progress).
A clue was found in the Fault Isolation Manual. For the boffins:
A. Fault Isolation Procedure
(1) This EICAS message alerts the flight crew to configure the fuel system to establish a tank-toengine
fuel-feed configuration.
During flight, when the fuel quantity for the inboard main tanks becomes equal to the outboard
main tanks, the EICAS advisory message FUEL TANK/ENG will show (M1 = M2 or M3 = M4).
The flight crew action is to manually close crossfeed valves 1 and 4 and put the M2 and M3
override/jettison pumps to the off position. This will initiate a tank-to-engine fuel-feed
configuration until the end of the flight.
Airline X ALL; AIRPLANES WITH FQPU BLOCK B UPGRADE (SB 28-2182)
(2) The >FUEL TANK/ENG message contains logic to prevent fuel-feed configuration messages
from showing on short flights during takeoff and initial climb. The logic allows the airplane to be
established in an early tank-to-engine configuration when the inboard main tanks are within
1000 lbs (455 kgs) of the outboard main tanks.
Additional logic will maintain the fuel-feed configuration established on the ground for 8 minutes
after the airplane transitions from ground to air. Specifically, for 8 minutes after the transition
from ground to air, the status of the tank-to-engine alert bit shall remain the same as its status
prior to the ground-to-air transition. This will prevent the >FUEL TANK/ENG and >X-FEED
CONFIG messages from showing during takeoff and initial climb.
Airline X ALL
(3) The EICAS message >FUEL TANK/ENG (ADVISORY) shows when all of these conditions are
true:
(a) The No. 1 or 4 crossfeed valve(s) are not closed.
(b) All main tanks contain more than 2000 lbs (910 kgs) of fuel.
(c) Jettison mode is not active.
(d) The TANK TO ENGINE ALERT discrete is set (2-minute time delay).
(4) The TANK TO ENGINE ALERT discrete is set when these conditions are true:
(a) The airplane is not in refuel mode (the refuel control panel door is closed and/or the
airplane is in air mode).
(b) The M2 fuel quantity is less than 32,000 lbs (14,500 kgs) or the M3 fuel quantity is less than
32,000 lbs (14,500 kgs).
NOTE: M2 fuel qty is less than M1 VTO+2000 lbs (910 kgs) or M3 fuel qty is less than M4
VTO+2000 lbs (910 kgs).
(c) One of these conditions is true:
1) The M2 fuel quantity is equal to or less than M1 or the M3 fuel quantity is equal to or
less than M4.
Airline X ALL; AIRPLANES WITH FQPU BLOCK B UPGRADE (SB 28-2182)
2) The M2 fuel quantity is not more than 1000 lbs (455 kgs) greater than the M1 fuel
quantity and the M3 fuel quantity is not more than 1000 lbs (455 kgs) greater than the M4
fuel quantity and one of these events occur:
a) The fuel quantity processor unit is powered up
b) The CMC ground test >FUEL QUANTITY IND is performed
c) The refuel panel door is cycled from open to closed and in ground mode.
The FIM doesn't mention the 120 second time delays, but I'm sure they are still in there somewhere.
Cheers