Steve Fossett’s plane seems to be low on fuel:

Moore said fuel sensors in the 13 tanks onboard the single-engine jet differ from readings of how quickly fuel is burning during the flight. Moore said the crew has been forced to assume that 2,600 pounds of the original 18,100 pounds of fuel aboard “disappeared” early in the flight.

Where does 2600 pounds of fuel “disappear” to? Overconsumption early due to a cold engine, or stuck valve?