You've got a lot of folks giving you some good and some not so good advice. I believe the last thing you did before the engine
quit starting was to change fuel
filters as evidenced by your post #48. I'm suspicious that there is still air in your fuel
I've always had an extra person who pushes the starter button when I bleed the system. Is that how you are accomplishing it? If you crack the nut on the top of your injector, get good steady no bubbles fuel are you able to keep the engine
spinning via starter until you get that nut tightened? If the engine stops spinning before you tighten that nut there will be air between the injector pump
and the injector and the engine will not start. There are self-priming engines but I've not encountered one yet. Do you have an in line fuel pump
somewhere between tank and engine? You can test the line by installing a simple squeeze bulb in the line somewhere. Start pumping and see where the fuel leaks
from a line or a gasket
or a connection.
Even just a bit of air through a fuel line or gasket
leak around your filters will allow air into your system. The engine may start after bleeding, run for a little bit and then die.
I'm betting on there still being a leak somewhere between your tank and injectors.
Good luck in finding the culprit.