Tank was drained and cleaned and new screen installed about 2000 miles ago, along with new primer pump.
I wouldn't think the lines could be clogged if it's running great one second, then I turn it off and try to restart and nothing..

The next time it is warm and you want to start it try taking the fuel cap off the fuel tank.
If that does not work go to Alldata.com and check the TSB titles... one for your car may say ' problems restarting when warm' or to that effect....

From what I have observed on this site.I would just check to see if valves have too little clearance. Once engine warms very poor compression if valves not able to seat properly. Only should take a short time to do a check. especially if not done since heaven knows when. Just a thought.

Valves were adjusted about a thousand miles ago. and I set them a bit on the loose side, They *shouldn't* be tightening up .
I cleaned out the tank vent lines a couple of thousand miles ago, but it wouldn't hurt to try the cap trick.

tightens up with use but can't make sense of that. Is this so and, if so, will someone 'splain it to me?

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Jim

'49 170?(donated to church in Darmstadt '58)
'58 220S(crusher, after '73 fire[San Antonio])
'72 280SE 4.5
'77 240D
'81 300SD
'83 240D parts car

Wouldn't hurt to do a quick check on clearances....if you didn't tighten it down enough then may have closed up on you.....would hate to spend a few weeks chasing other possible things to find out it was this...

Usually its good troublshooting to look at what was done last when you have something that goes wrong not long after some work was done.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Not familiar enough with this type engine. Just a few other thoughs though and not meant to frustrate you as you may have covered already. I would warm up and shut down. Remove return line from injection pump and see if any fuel discharge when cranking hot. Just primarily verifys lift pump is not going down when engine hot I think. If your problem was quitting on road only would suspect back pressure (blowby) shutting down pump with perhaps semi obstructed bypass system as a possibility. I do not think engine can retain blowby pressure after shutoff when warm but you may want to verify again because it is so easy to do. Simple as removing oil fill cap prior to trying hot restart..

i am always looking for the simple thing... could be algae in the tank. you said you cleaned it but did you buy fuel again from the same place? perhaps too obvious a question but such a simple problem is easily overlooked.

good luck.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Tronteck, as the valve rocker pounds up and down if the adjuster is not tight the thread starts to travel in the tighter direction (less clearance) on mercedes gas engines. Mercedes used to specify clearence checks every 10k if i remember. Ignore this and pull head to change the burnt sodium cooled exhaust valve before another ten K was travelled in many cases. At some point mercedes made the interference fit of the adjuster threads much tighter and they became a bear to adjust but lessened the problem enormously. The diesel uses a different set up of two nuts pressured together with two wrenches to lock the setting called a jamnut arrangement i believe. If not tight enough the adjuster thread starts travelling again decreasing the clearance even on that design I believe. One might be prone to think the clearence would loosen and increase but the reality is it moves towards reducing the required operating clearence.