After a bit of poking around in the Manager.xml, I think I may have found the culprit for the incorrect fuel numbers. There may be a phantom fuel tank added.
Here is an entry that I think calculates the fuel and this is what it reads, just after installing the Accu-Sim pack that you buy from A2A.
<GaugeString>\{clr=yellow}FUEL TOTAL: \{clr=white}%((A:FUEL TANK CENTER QUANTITY,gallons) (A:FUEL TANK CENTER2 QUANTITY,gallons) + 1.2 /)%!d! Imp. Gallons\n
Top Tank: %((A:FUEL TANK CENTER QUANTITY,gallons) 1.2 /)%!d! Imp. Galls (%((A:FUEL TANK CENTER LEVEL,percent))%!d!%%)\n
Bottom Tank: %((A:FUEL TANK CENTER2 QUANTITY,gallons) 1.2 /)%!d! Imp. Galls (%((A:FUEL TANK CENTER2 LEVEL,percent))%!d!%%)\n
</GaugeString>
After updating with the latest on-line updater, we get an extra calculation for a third fuel tank added to the mix. Here's the code with the suspect bit in yellow.
<GaugeString>\{clr=yellow}FUEL TOTAL: \{clr=white}%((A:FUEL TANK CENTER QUANTITY,gallons) (A:FUEL TANK CENTER2 QUANTITY,gallons) + (A:FUEL TANK CENTER3 QUANTITY,gallons) + 1.2 /)%!d! Imp. Gallons\n
Top Tank: %((A:FUEL TANK CENTER QUANTITY,gallons) 1.2 /)%!d! Imp. Galls (%((A:FUEL TANK CENTER LEVEL,percent))%!d!%%)\n
Bottom Tank: %((A:FUEL TANK CENTER2 QUANTITY,gallons) 1.2 /)%!d! Imp. Galls (%((A:FUEL TANK CENTER2 LEVEL,percent))%!d!%%)\n
</GaugeString>
After removing the suspect calculation, all variants show the correct fuel quantity of 85 gallons max. Perhaps the guys at A2A did experiment with the possibility of a Slipper tank as suggested.
Anyway. I will try it out with the code removed and see what happens. Currently crossing the US, east too west. A slipper tank would be really useful though.
Cheers.
Steve.