Need a little help, I'm using my Dad's '90 Dodge with a Cummins BT 5.9. It stopped cold on the highway yesterday, no hesitation. I've primed the filter/seperator. Worndering what's next, lift pump or injection pump. Is there an easy way to rule things out and try to fix it myself?

 

I don't know a lot about 1st gens, but I think you're on the right track by starting with the fuel system. Have you checked the filter to see if it's clean, pressure...do you have a fuel pressure gage? Have you cracked an injector line to see if you're getting fuel to the injectors?

 

Make sure you have power to the shutoff solenoid at the back of the pump. There ought to be 12 volts there when the key is on. It's not uncommon for the terminal just to fall off. If that's all good, throw a fuel filter on it and see what happens.