Ok look for several things first make sure you have base engine oil pressure. If so then you need to check for leaks in the hp oil system could be a branch tube or som,ething of that nature. If you find nothing then I would say replace the pump. If its under 12000 miles since that last replacement you can use SPW (service part warranty) to replace it.
Im just guessing you work for a dealership. If not then replace the pump anyways it will just cost them.
How did they screw up an injector on a 6.0L? Ive done it on 7.3 before by putting the bolts in the wrong spot. and the snap........well we all kn,ow how things happen on these trucks.