Neutral switch is in the transmission. Hold the key to start position and move shift lever to see it it starts. If it does it's a simple adjustment. My Bluebird has a pinch bolt on the cable end. If it's similar, put shift lever in neutral, loosen the bolt, put put trans in neutral and retighten bolt.
Also, when the bus is running (bypassing everything) after the pressure builds, the accelerator speeds up and continues to speeds that I fear would be dangerous, so I shut it down. What would cause the engine to automatically accelerate after the pressure builds?
If it is you probably have some air lines crossed.