what happen when a diesel sit for a while it gets sticky but once it warm up it will losen up like i say it sound to me the open and close part of the pump is stuck close so it is not letting the pump to build up pressure to pop the injectors you need to find the away to the part that will let you check the part of the pump that pushs the rack to the open postion i dont know how you pump is set up there are so mean diff type of shut off system so use vac some use eletric