Pop pressure of Injectors When you look at a 24V Cummins fuel injector and look at how it's designed and how it functions. The injector pintle is held shut by spring pressure. For stock injector, you need 310 bar (4,500 PSI) to make the injector open and release fuel into the cylinder. Now the bottom limit is 293 bar (4,250 PSI) below this point the automation gets poor and there is more smoke because the fuel can't be heated enough to get vapor to go BANG! As injectors start getting lower