The motor is gettin plenty of fire and fuel to the injectors but injectors not opening what could cause this. i have replaced all fuel filters and relay also the pump

Is the code still active, and are the injectors opening ?
Will it start using starting fluid ?

r u sure that fuel is not gettin to the inj? what motor what car, it could be a HPOP (high pressure oil pump) that is what opens the injectors on some applications could have leak in the fuel system and its sucking air instead of fuel filter clogged with gel or bacteria, and r u sure you put diesel in it and not gas by honest mistake?

loosen the 2 bolts about at the rear of the exhaust going to the catalytic converter and then try to start the car (highly recommended you wear ear plugs) if it fires up right away your caty is clogged. believe me i just went thru what you are going thru. i replaced everything but the motor. another thing to try is pull the fuse for the injectors. if the car fires up and dies or if its acting like its gettin too much fuel replace the fuel regulator on the fuel rail and then ream out the catalytic converter

Make sure it has plenty of oil. Low oil level will cause injectors to not fire. Change fuel filters > small one on top and big one on frame rail..

Purge air by leaving engine filter loose. Fuel should come squirting out once key is cycled, if not tank could be stopped up.

unplug the fuel injectors, check the olhms on all. the readings should all be the same, around 11-11.5 olhms. Any readings that are higher is a sign of a bad injector which is what your problems sounds like., putting to much fuel to a cylinder causing different fuel amounts to each cylinder and causing it to backfire out of the throttle body , excess fuel . Also remove the throttle body and clean with cleaner and a toothbrush after replacing any injectors. Or there's a simpler answer and that the cambshaft is worn-out/round causing the lifters not to open enough to let in all the fuel. A worn belt would not cause misfires only on select cylinders but rather jump timing, slipping a notch on a gear and possibly bending a valve or valves and this cause a loud clacking or a really a sign to quit running the motor because it's broke! Good luck.

SOUND LIKE A INTAKE MANIFOLD LEAK.WHICH WILL CAUSE BACK FIRING.FUEL INJECTORS COULD BE STUCK OPEN DUE TO CARBON BUILT UP ON INSIDE OF THE TIPS.TRYING CLEANING INJECTORS ADDING A BOTTLE OF FUEL INJECTOR CLEANER IN A FULL GAS TANK.ONCE YOU GET ENGINE STARTED DRIVE TRUCK AROUND TO LET THE INJECTOR CLEANER CLEAN INJECTORS.IF THIS DONT WORK.YOU COULD HAVE A BAD INJECTOR STAYING OPEN.HAVE TO BE REPLACED.

Check all the fuses,and check the fuel pump relay,if this checks out o k,See if there is fuel pressure at the fuel injectors,if there is,then the injectors are not pulsing.The cause of this is the pick up coil in the distributor,but replace the distributor as a whole,this has all the components in the distributor,That control the fire,and the pulse to the injectors,A used one might be more economical sound money wise.

Check the electric stop on the injector pump is working.

there are two things i would do
first is the cheaper get a can of starting fluid and while some one chanks the engin and steps on the gas pedal lightly spray the starting fluid into the air intake after the air filter ( remove the air filter cover first) it should start and die when the fluid runs out
#2 get a fuel injector noid light to see if the injectors have power to them
ihope this helps you

Since you have replaced all those parts already, I would suggest checking out the egr valve. Also I was wondering how the coilpacks or distributor are acting? Is the truck firing on all cylinders? Very possible you have leaky injector also.