D750B Tries to start but won't catch

Sgt, sounds like you're real close to hearing the sweet noise of your engine running. I'd suggest you go through the process of bleeding the the air out of her again. You may be close enough to a start you could simply loosen the nuts at the injectors and turn the starter over for 15-20 second intervals a few times. When you see fuel dribbling out of each line, tighten them up.

This process is easier on the starter if you have the compression release pulled out.

Any chance i could be something like valve adjustment?
Set too tight, and not sealing? Unlikely, just askin is all.

Did you replace the small return lines off the injectors?

Prime the injection pump, bleed the injectors, then remove the injector lines from the injectors and crank, see what happens.

I had a couple bad injectors in a John Deere engine ( in a LULL ) that engine compression was pushing back thru the injectors ( 3 of the 4 ), I bled multiple times, my boss bled, multiple times, pulled injectors out and connected to lines, and crank to check spray pattern ( field job at a construction site, not real pretty but effective ) put one injector back in and snugged it down, cranked again testing another, fuel came shooting out of the injector that had been installed ( but not connected to injector line ) took all 4 injectors to diesel shop, they tested and all failed, basically the poppets had failed and the engine compression was pushing back into the fuel system.

Something to check.