Hello all,
Hopefully somebody can help me here? I've been through the forums to no avail.
Just invested in the 737-200 adv on FSX, and I am unable to start the APU. 
I've set the default cessna with everything off and saved as default.  I then open the 737-200. I'm switching on the battery and the master avionics. EP is available. GRD power is on, APU bleed air switch in on. Fuel Pump 1 is on.
APU start button does nothing at all at this point.
I guess I'm missing something somewhere, or using the wrong sequence!
Advice for the newbie please.
With thanks

Turn on the No1 AFT and FWD fuel pumps, and No2 AFT and FWD fuel pumps, and the APU should start. That works for me.

Thanks for that - I'll give it a go!

Sadly it didn't do the trick.
I've managed to get around it by loading the cold and dark default tutorial flight, and just changed the location and livery to suit, and then saved it.
I'm guessing there's something in the set up I was using that wasn't working.
Thanks anyway!
Christopher

Hi,
Since my last post, I'm continuing to have trouble.
I'm opening the default C&D cessna flight, then changing aircraft to CS 737.
I then switch on avionics, turn on EP on the simicon menu, turn on the battery, turn on all 4 fuel pumps, turn on the Ground power switch....and then the APU switch with no response.
Any more advice please?
With thanks
Christopher

Are you spending time getting ready for the flight, then when you are ready for pushback, you try to start the APU, so you can start the engines during pushback? Therefore quite a bit of time passes before you actually try to start the APU.

It's possible, that if there is some time passing, between the time you load the 737 into the sim, and then get around to starting the APU, that the main battery is losing power, even though you're connected to the External Power supply. You could try adding the line electric_always_available=1 to the aircraft.cfg, under the [electrical] section. Like this:

[electrical]
max_battery_voltage = 24.0
generator_alternator_voltage = 30.0
max_generator_alternator_amps = 400.0
avionics_bus=0,1,17
avionics=1,1,17
flap_motor=0,1,17
gear_motor=0,1,17
autopilot=0,1,17
pitot_heat=0,2,17
additional_system=0,1,17
marker_beacon=1,1,17
gear_warning=0,1,17
fuel_pump=0,1,17
starter1=0,17,17
starter2=0,17,17
standby_vacuum=0,1,17
hydraulic_pump=0,1,17
fuel_transfer_pump=0,1,17
light_nav=0,1,17
light_beacon=0,1,17
light_landing=0,1,17
light_taxi=0,1,17
light_strobe=0,1,17
light_panel=0,1,17
light_recognition=0,1,17
light_wing=0,1,17
light_logo=0,1,17
light_cabin=0,1,17
directional_gyro=0,1,17
directional_gyro_slaving=0,1,17
electric_always_available=1

That way, the main battery, should never run low.

Note. I open the aircraft.cfg with Notepad. After making the changes, select Save (not Save As...). Also. Always backup the aircraft.cfg BEFORE you make any changes to it!