I have a 1994 gmc 6.5 turbo diesel I had problems with it dieing driving down the road I replaced the pmd and still had the same problems just less. The other night I started it up it ran for 20 min and as soon as I put it in drive it died,.I cranked and cranked it wouldn't start a couple days later I walk outside and it starts on first crank and it died again and won't start back now? It turns over good and as it should it just won't start !!!! Help me please!!!!!!!!

 

The ignition switch is a mulit contact switch that can burn out on any of the contacts.
the contact that feeds the ECM,IP ect is a common failure point.

Your problem does sound like another PMD failure though.

Where did you mount the replacement PMD?
Did you use heat transfer paste/pad between the PMD and what it is mounted to?
Did you replace/re-install the resistor in the PMD connector cavity?
Is the PMD mounted to a heatsink?
If so is the IP harness ground mounted to the IP or the heatsink(big NO-NO)?
Is the heatsink mounted in the engine compartment or remotely mounted outside the engine bay(best location).
Google 6.5 diesel lift pump test and perform it.

 

I put my new pmd in my bumper with all new wire harness to it. I checked today and the truck is getting fuel up to the filter before it completly stopped running it used to cut out when I gave it exess fuel.