CM 870 hard start issue

[Chamberpains]

Im curious what you mean by hard start? Slow or sluggish cranking? Long cranking time before actual engine start?
Here's a link for your fuel system. Just so you know how things flow and why. The pressure regulators can be pulled out and cleaned if not replaced rather easily. Just so you can see if you have junk in the IFSM and maybe one clogged.

https://youtu.be/HvvFElrc5ak

Also I'd be curious what your voltages are to the 12v ecm wire. Sounds like when you play with the wiring or have extra power you state your truck fires off normal. Without Insite or another diagnostic tool your gonna have to check voltages with a multi-meter.
Also does your Davco or water seperator stay full of fuel after the engine is shut down? There is a ball spring valve (anti bleed back valve) inside the inlet side fuel line fitting on the Davco. I just found mine 2 days ago and had it stick when I reinstalled it after cleaning it.