does anyone know where i can find tech info for an isuzu npr? i will try here, maybe someone knows.

i have a 2000 4cyl npr diesel. it is not getting fuel? i cracked the #4 fuel line loose at the injector and started pumping the primer. at first i pulled up on the primer and it seemed like a vacuum was sucking the primer back down, after pulling up and it going back down on its own several times, it finally seemed like it got some fuel in it and i had to press it back down, once that happened, fuel came out of the line, i tightened it back on and the truck started right up. the next day, same thing, no start, like it lost its prime? did the whole process over again but this time the primer never got fuel, i tried for a long time, all that happened is i pulled up on the primer and a vacuum like action pulled it back down, no fuel? what could be the problem, bad primer, should i put a in-line elect. fuel pump, if so which one is recommended?

thanks.