FSX - If I start the APU from the Cold and Dark without turning on the Left DC Fuel Pump, the APU Logic automatically turns this pump on. Should the associated PRESS Light not turn off with turning the APU start switch to ON, as the pump starts and delivers fuel, ie fuel pressure and flow is available? With the CS 757, the pressure light only goes out when the APU is running.

Manual Part II

Page 183 APU Start "DC fuel pump is energized when the APU Selector is placed in the ON position if no AC power is available."

Page 508 APU Fuel Feed
"On the ground, with the APU selector ON and no AC power available, the DC pump runs automatically."

FraPre wrote on Apr 21^st, 2019 at 4:11pm:

FSX - If I start the APU from the Cold and Dark without turning on the Left DC Fuel Pump, the APU Logic automatically turns this pump on. Should the associated PRESS Light not turn off with turning the APU start switch to ON, as the pump starts and delivers fuel, ie fuel pressure and flow is available? With the CS 757, the pressure light only goes out when the APU is running.

You’re confusing AC fuel pump with DC fuel pump. The DC fuel pump (there’s only 1) has no indicators or buttons. What happens is:

1. Cold and dark, battery on, standby bus auto, APU selector to start/on.
2. DC pump immediately comes on, all 6 AC fuel pump PRESS lights should be illuminated since there’s no AC power.
3. APU is fully started and you have AC power, now the FWD left AC boost pump PRESS light extinguishes, and the DC pump (which you can’t even tell it’s happening) turns off.

Yes, right, I forgot to connect the external power. It works with external power and thus AC voltage.