Is center tank fuel required to start the 737-800 engines? I have been doing some flights with the 737-800 and when there is no fuel in the center tank, the engines won't start. Is it like that in real life?
(airliners.net)

Be sure to turn on the appropriate pumps on the lower-left of the overhead panel. The APU can start without them via suction.

Otherwise, it's a simulator problem.

Also see: Why are fuel tanks in the wings filled first, and why are they used last?