Astro van will not start after sitting a few days. When it does start, I can start & stop all day long. Hear fuel pump running and after much pedal pumps,when I shut it off it starts to diesel. Almost fires up. New fuel filter in the right direction. Just in the past few days it will not start at all. New fuel pump relay. Sensors? The van is such a treat to work on, you need a set of 4yr old hands to get into some spots. I'm totally stumped. What area to look at next?

 

Just because you hear the fuel pump running does not mean it is pumping at the correct pressure. Do a fuel pressure test. It could also be the fuel pressure regulator.