They indeed do have something in common. The crankshaft turning in the injection pump is it. I would rather see you not get into the injection pump yet.

The diffinative test is to find out if the lobe that powers the lift pump is turning when the engine is rotating. Your simplest approach to this might be to remove the lift pump. There are other ways but that one has less potential of things going wrong in any way. Plus it is a pretty conclusive test.

Glad to hear you had someone else crank the engine by the way. Seems you did follow the limited protocals of the test so all is good so far. By and large though the injection pump does have an issue of some sort at least is proven as far as I am concerned. You are closing in on the target now. Lets see if that crank is turning in the injection pump first or not though. If not it is an unusual failure but still a possible one.

The benz is fixed. Thank you all for your help and support. I need to take pictures to write up properly what the problem was. In short, I did a few more tests and realized that the lift pump was functioning, but fuel was not getting through the IP. I was able to locate a clog. The clog was an unusual one which resulted from modifications made by the previous owner. In the near future, I will write a detailed explanation with pictures so if anyone every encounters this, the solution will be here. Thanks everyone!

Congrats! I'm so glad you solved the problem, and I'll look forward to the write-up.

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"Senior Luna, your sense of humor is still loco... but we love it, anyway." -rickymay ____ "Your sense of humor is still loco... " -MBeige ____ "Señor Luna, your sense of humor is quite järjetön" -Delibes

1982 300SD -- 211k, Texas car, tranny issues ____ 1979 240D 4-speed 234k -- turbo and tuned IP, third world taxi hot rod

2 Samuel 12:13: "David said to Nathan, “I have sinned against the Lord.” And Nathan said to David, “The Lord also has put away your sin; you shall not die."

Good detective work. Frustrating but cheap I suspect. The upside is you have learnt a lot more than you did about the fuel system in the process.

You're killing me. All you can share with us now is a "clog?" When I find clogs in my car it usually means I had a good time last night. Details please.

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83 300TD, 260,000 miles, aka "Dusty"
6 vehicles, 2 cup holders (both in the dump truck)

@marfa300td sorry for being so vague, i just want to do a proper job explaining the problem and I don't feel I can do that until I have taken pictures (and finished come loose ends to evaluate the condition of the vehicle, it did run, but under load it eventually died after about 100 miles, i think probably a filter clogged) i will give a better explanation of everything later with pictures, but for those curious now, on top of the spin on fuel filter, there is a 3-way inlet allowing fuel to return from the back of the IP, and the injectors, and allowing fuel to return to the tank. the previos owner had removed one of the 3 lines on this 3-way connection (which actually has a 4th way technically into the spin on filter through a small hole) and switched it with what is usually the fuel supply line. he switched the return to the tank with the supply line. in doing this, the previous owner made the only pathway for fuel from the tank through the small hole between the 3/4-way connection and the spin on filter. for anyone who has ever taken this connector off, the hole is "pinhole" sized. i believe that although i took this connection off and cleaned it at some point, i believe this clogging may have been my issue. in the end the solution was to switch back the two lines. it seems stupid that i went through all this work for something this small, but i will say it ran fine with the previous set up for a while, but i think sediment found its way forward. in any event, the car did die last night, but its 15 degrees here. i will take pictures and try to diagnose why it dies, but i am feeling a lot better. much thanks everyone, and a better more organized write-up is to come