Heya Wilderrobb,
I can't really tell you truthfully unless I know what Gulfstream you're using and what type of fuel gauge it has on its panel.
It totally depends on the fuel gauge that's on the panel that you're using. If it's the circular analog type that shows pounds of fuel remaining (like the Beech King Air 350 Fuel Gauge) you may not see a change since it may be "maxxed out" (above the number of pounds registered on the gauge). Until you "burn off" some fuel the gauge will read full.
Near the beginning of August I downloaded and installed the outstanding Gulfstream IV by Rick Sasala (with FDE and textures by Roger Mole). You can find it here on SimV:
http://www.simviation.com/fs2004jets60.htmJust my opinion, but, this is one sweet bird aside from the fact that the Aircraft.cfg was a little off in relation to Empty and Max Takeoff Weight, and fuel capacity. I checked the numbers related to FAA Type Certificate Data Sheet No. A12EA found here:
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/8fd4bfcd72b4d55b86256d980067723d/$FILE/A12EA.pdfI figured that these guys should be trusted to give the correct aircraft specifications. I plugged in the new numbers and the aircraft still flies great (with very little tweaking)! And yes, folks, I do "check the numbers" on every aircraft I download.
The panel that is supplied with this aircraft has a digital fuel gauge which will list the total amount of fuel in pounds. This is useful in that you can change the amount of fuel capacity in the Aircraft.cfg file and the change will be reflected on this gauge.
Mike Stone also has an excellent Gulfstream V (I don't know if it's available on SimV) but you can download it from his webpage:
http://www.pmstone.comJust as a note I found that the Aircraft.cfg supplied with Mike's Gulfstream V was pretty darn close to the numbers on the FAA website.
Mike Stone's Gulfstream V also has a digital fuel gauge on its panel.
The default 737 panel also has digital fuel gauges.
In conclusion, you may not see a change on analog type gauges, however, if you use a digital fuel gauge you should see the difference.