Christian, Just want to make sure I understand your bleeding procedure. The air bleed valve, with the famous knurled knob, appears to be just where the fuel line from the secondary filter enters the injector block. So by turning the knurled knob, in theory, that should have the same effect as loosening the fuel line in your procedure. But now I am back to my original question, turning the knurled knob has no effect on my engine so I loosened the nut holding the knurled knob, am I doing the same thing as you suggest? And does this one bleeding procedure work if you change both the primary and secondary filters, or do you have to first loosed the air bleed plug (hard to get to) on the secondary filter first? I understand the part about refilling both the primary and secondary filters with fresh diesel first, makes sense. Still wondering how to get the knurled knob on the air bleed valve to work? Turning the knurled knob seems like a better way than loosening the nut.
Also, I do not see the lever supposedly on a a mechanical lift pump mounted to the engine, maybe I dont know what to look for. I do have the electric fuel pump mounted close to the primary filter. I have the photo with call outs from the Universal engine manual but dont see any call out for this lever, can you describe where I should look?
Presently I wired a simple on/off switch to a long cable with alligator clips at the end and "short out" the starter key switch at the engine panel in the cockpit from my position at the engine, saves having the admiral do that with the key switch, that turns on the electric fuel pump. If the lever does the same thing saves me some work connecting my jumper switch to the key switch. I understand from your comments that that lever is poor but if you refill both filters with fresh diesel, that might work ok, if I can locate that lever.