I pressure the fuel tank and bleed air out, at the back of the injection pump. IF, fuel doesn't pour out of that line, then there's something blocking it from getting there. Then, I crack a couple lines at the injectors, and crank it over to bleed the air from the injection pump to the injectors... The engine may/probably will start on what ever cylinders that you didn't open the lines to.
As a side note: one time my dozer wasn't running right and I changed the fuel filters, it didn't help. Then I found a "small" screen "in" the pump at "inlet" of it! I took it out and it looked clean, BUT I washed/brushed it good, blew it out with air pressure, reinstalled it and the dozer has run fine ever since!
SR