When trying an APU start of engine 2, I get a start press low alert. Specifically, engine 1 running and pack 1 auto, pack two off and ISOL valve closed. Why won't the engine start? I know this is common practice on very hot/cold days in the Boeings, (to have one pack isolated and running to provide some air), and looking at the schematic of the 717 with the APU bleed supply being to the right of the ISOL valve, it should also work. Any ideas?
Pic 1: APU supplying the right side of the manifold with enough PSI for engine start
Pic 2: A few seconds after pulling the engine 2 start switch, the PSI drops as it should, and N2 only rises to about 4%, then drops back to zero. Pretty sure in the real plane #2 would have no trouble starting.