Firstly. I take it that you are loading the 707 with the engines already started then?
Secondly. There is a "procedure" to starting the 707. At first I couldn't always get it started. Now I start them first time, every time.
Here is what I do:
Shift + 2 (Animation Panel)External Power ON. External Air ON.
FE PANELBattery.....ON
External Power.....ON or Ground Service (I usually just place the switch to the ON position)
DC Meters Selector.....TR ESS
Essential Power Source Selector.....EXT PWR
AC Paralleling Selector.....EXTERNAL POWER
All 4 Engine Bleed Air switches.....ON
Wing Valves.....OPEN
Left & Right Air-Conditioning Unit Pack Switches.....ON
CONTROL STANDEngine Start Levers....START/IDLE (CTRL+SHIFT+F4)
OVERHEAD PANELGRD START....LOW PRESS
Engine Start Control #3...GRD After engine #3 starts repeat for engines #4, #1 & #2
FE PANELDC Meters Selector.....TR3
Essential Power Source Selector.....GEN 3
AC Paralleling Selector.....GEN 3
External Power.....OFF
Galley Power.....ON
Shift + 2 (Animation Panel)External Power OFF. External Air OFF.
That should get your engines started for now. I quite often wait for N2 to reach 15-20 before switching the Engine Start Levers to START/IDLE .
Hope this helps.
Mark
EDIT Oct 3rd, 2010 at 4:29pm: Moved External Power.....OFF to the correct order of the procedure as pointed out by Alberto! Thanks.EDIT2 Oct 6th, 2010 at 7:45am: Added the Left & Right Air-Conditioning Unit Pack Switches.....ON into the start-up procedure. I somehow thought that they and the Wing Valves were the same switches. Sorry.