Been chasing a 1093 low fuel pressure code on my 2004 LB7 w/ 118,000 miles, no lift pump, recently swapped out original injectors for SAC00 and rebuilt fuel filter base with new AC Delco fuel filter. Original symptom was a high pitch whining coming from right side of engine when engine speed was ~3000 RPM or higher. Never had this issue before the injector swap. Later, a 1093 code set which pointed toward fuel system and not a boost leak. Did the usual test of commanding 160 MPa at idle to see if the CP3 was going out. Luckily, the CP3 was able to hit 160 MPa without any issues. I then went ahead and swapped out the fuel filter as that is the usual next step. There is just a slight hint of the high pitch whine at ~3000+ RPM and the CP3 actual fuel pressure was able to match the desired. One thing I did note between the original fuel filter and the new one that I replaced it with was the o-ring seal. The one I took off had a round o-ring cross section while the new one had a more triangular shaped cross section. FWIW - the triangular shaped design fits better into the filter than the round design.
Question: are there any quality issues with the AC fuel filters? I know over the years that they have improved them quite a bit and added more filtration capability due to all the original injector issues. Do these filters now have more restriction in them that makes a factory non-lift pump truck more sensitive to low fuel pressure at higher RPMs? Would just adding in a lift pump be the recommended fix, or is there something else going on to check into?
Question: are there any quality issues with the AC fuel filters? I know over the years that they have improved them quite a bit and added more filtration capability due to all the original injector issues. Do these filters now have more restriction in them that makes a factory non-lift pump truck more sensitive to low fuel pressure at higher RPMs? Would just adding in a lift pump be the recommended fix, or is there something else going on to check into?
