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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?

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    $\begingroup$ So you did them in a simulator? In which simulator? $\endgroup$ – Jan Hudec Jan 20 '18 at 20:38
  • $\begingroup$ In X-Plane 11, Zibo's 737-800 mod, I can fly with no fuel in the center tank. :-) $\endgroup$ – Marco Sanfilippo Jan 22 '18 at 13:29
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No, it is perfectly normal to operate without any fuel in the center tank. Until your fuel load is over about 17,000 lbs, the center tank should be empty. That’s enough for about 2 hours of flying, plus reserves.

If your simulator requires fuel in the center tank in order to start the engines, it isn’t accurately replicating the real aircraft.

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enter image description here(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?

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  • $\begingroup$ Thanks!Seemed to be a bug and thank you for the extra article! $\endgroup$ – Alberto Nieto Jan 25 '18 at 15:11
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If you let the center tank go completely dry you’ll get an EMDP malfunction along with an overheat warning. (See ELEC 2 & ELEC 1 hydraulic pump switches on the overhead panel).

The EMDPs are cooled using what are best described as fuel cooled heat exchangers. The temperature sensor for the EMDPs is monitoring the temperature of the case drain fluid, which reflects the source of greatest heat output on a normal pump. There are a number of events that will cause the EMDP to overheat:

  1. Every time you cycle the pump from OFF to ON, it increases the pump temperature briefly. Cycling the pump off/on repeatedly without allowing adequate time to cool will cause the overheat indication.
  2. Operating the EMDP without sufficient fuel in the main tanks (from memory: 1,675lbs) will also cause overheating because the fuel quantity is insufficient to provide an adequate cooling mass to the heat exchanger.
  3. An internal failure of the pump might also cause the overheat light.
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  • $\begingroup$ In the 1st paragraph, you say "center" tank & that's incorrect - fuel in the center tank doesn't cool the electric hydraulic pumps. Later in the answer you discuss the role of the main tanks cooling those pumps, and that's correct. You may want to edit that first paragraph. $\endgroup$ – Ralph J Nov 24 '18 at 6:15

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