We have an '82 300sd that will start great and run great when cold, after it warms up , if you try to restart it , no go. cranks over fine, just won't cough. and now it is also shutting down when going down the road after getting good and warmed up.

I had posted awhile back ( just got around to checking the thing ) and had some suggestions about possible residual vacuum going to the shutoff valve and possibly rack dampner screw too tight and binding rack.

Today I tested it for vacuum... no vacuum going to the fuel shut off while cranking, good vac to it when turned off.

Made sure the manual shut off wasn't binding.

Backed the rack dampner screw out .

No change, still wouldn't start warm.

Cracked a few injector lines loose to see if it was getting fuel while cranking. Some fuel drizzled out around the fittings, but not with the gusto that I would expect.

Could I be looking at a failing fuel shutoff valve, possibly the spring inside it so worn that it can't kick the thing open when warm??
Any other suggestions?
Thing runs great other than that. fuel filters are new and injectors all rebuilt within the last thousand miles by a very good Bosch injection shop.

Thanks---------Robert