Unfortunately, in FS2k, it is not that easy. You have to edit tables 1502-1507,
and these are not the easiest format to adjust. Further, because these
interact, you may have to do multiple adjustments to get accurate N1 and N2 and
fuel consumption and performance? You can do some adjustment with intake throat
area, but this may throw performance off if it is out of appropriate range for
that engine. You might experiment with 1522 switches, I am not sure what effect
they will give. Most of what you need to change is in 1503 and 1504.
I recently got hold of a 757 air file but the fuel consumption is way too low.
I have both 'Flight Dynamics Editor' and 'Air-Ed' but i have been unable to
find an entry which will modify this. I tried increasing the thrust of the
engines but this obviously makes the plane too fast, so i increased drag, whichmakes it hard to handle at low speeds. It would be a great help if anyone knew
the entry in any of these editors to change the fuel consumption rate.