747-400 range performance

According to online sources, a 747-400 should burn about 20,000 lbs of fuel/hour at maximum range cruise of Mach 0.80 at 35,000 feet. Using those parameters in FS2002, I get less than 8000 lbs/hour. I was able to complete an unrefueled around-the-world flight (49 hours!), which the real bird would certainly never do. is there a patch for this anomaly?