I've been researching info on my 1995 E300D's current maintenance issues & found this info on superturbo.com the link is:
What caught my attention was his comments on bubbles in the fuel flow.
OM606 fuel supply issues
Thread starter had the username of 'AlanMcR' on that site.
I haven't gone deep enough to know if there is merit to the claims, but with my 1st reading it does provide insight on how the fuel flows & some of the pitfalls in my cars fuel system.
Based on his comments I'll probably make a few changes to my fuel delivery system once I start that portion of my required work.
I'm currently trying to make a list of injection pump related o-rings, shut off valve issues, lift pump, return hoses & connections to hopefully have parts on hand once my work starts. Besides the delivery valve seal leaks my fuel tank seems to build excessive pressure at times.
I also think I caught a lucky break this past weekend, I was showing an older finish mower to a local guy that mentioned he had moved here recently & made his living working on older car chassis & driveline components. Turns out he has experience rebuilding Mercedes transmissions & other components plus he offered to 'help' me on my projects. What a find if it proves out. I'm glad that I had given him the finish mower before we started talking about cars.