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I have a 1980 300td wagon that sat half the winter. It now starts, but then dies, suddenly, after about 3 or 4 seconds. The same thing happens when I leave it at a low idle or rev it up. Fuel is flowing from tank, through freshly changed filters to hp pump and all injectors have been bled. Is there a vacuum control on hp pump that could be stuck (ignition off?)? Could my return line be blocked (I've had it off and blown on it, and it had some resistance)? My next attempt will be a heavy dose of injector cleaner in the filter and see if that frees anything up, but I'm at a bit of a loss. Again, the shut-down is instant, not like it is bogging down, starved for fuel, and then quitting. It is more like the key is turned off.

Any help or suggestions are greatly appreciated.
 

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OK. I just found the vacuum diagrams posted above and see that the valve on the top of the fuel pump is called the vacuum modulating valve and also that there is a switch-over valve ahead of it. Could these cut off fuel completely?
 

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usually fuel is only cut off by the vacuum line on the rear of the pump, this happens when the key if turned off which pulls the fuel rack internally and shuts off fuel. I believe that vacuum hose is brown ? You can get diesel purge and run your car directly off of that, it gives great results, I run the car for about 1/2 hour on a single can. Where the fuel lines come from the tank you put the feed and return lines both in a clean container and fill with diesel purge (made by lubri moly I believe) and fire the car up. These old diesel usually either run or don't run, so this should help. good luck.
Trent
 
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