I have a 2002 748 with some fuel issues. The tank and pump are working fine. The lines to fuel injectors are correct. Throtle body operation check good reading correct mv on pins -16 and +30. For some reasons I´m getting know indication of the fuel injectors. How do I test signals to injectors? Could they be clogged? Does a back pressure from regulator in tank must be preasant for both to work?