I will go first. Diesel bus would not start. Charged batteries. Tried ether. It would rev up and then immediately shut off. Tried to get it started with annoying old curmudgeon coworker for hours in the dark and cold. He wanted to change the batteries, which were new. I went home and slept on it. It seemed to be deprived of oxygen. The next day I went out to the bus and traced the intake of the cummins engine to where it enters the engine. I assumed, from looking at a detroit previously, that a throttle body was there that mixes oxygen from the EGR with air from outside. I tapped it with a small hammer. The engine started right up. The throttle was stuck closed.