My SD has it's moments of fuel pressure loss. You can be crusing down the interstate and suddenly feel a power loss that lasts less than 1/2 second...something exactly like taking your foot off and back on the throttle. Also, at cold start it's very rough and needs to have enough throttle to keep at least 800-900 RPM to run somewhat smooth and not die. Glow plugs are barely 2 years old and the injector pump and injectors were replaced by the P/O (maybe 50kmi ago). I've replaced all the rubber fuel line from tank to primer in the last 8 months. I'm thinking from my experience in the semi-diesel world that I have a lift pump that's weak. I read 07.1-145 "Checking fuel pump and bypass valve" and it seems that the bypass valve can get clogged and needs to be cleaned and the spring lengthened to increase tension. Is there anyone else that has had an issue similar to this where cleaning the bypass valve fixed the issue or did they have to replace the fuel pump?
(btw fuel, primer, & lift...they all mean the same thing in the big diesel world) TIA all, -- Luther KB5QHU Alma, Ark '83 300SD (230,xxx kmi) '82 300CD (158,222 kmi) '90 300E & '82 300D (parts or run?)