Truck Repair: black smoke, fuel dilluted oil., rich fuel mixture, fuel injection pump

Question
Hey Cliff, How's it going? My father just bought a 1989 Dodge Ram with the Cummins. mileage on odometer is 27k+, but odometer also only has five digits so it could have 1,2,or 3 hundred thousand. I'm not familiar with the repair history. The problem I wish to address is what I perceive to be as a rich fuel mixture. The symptom is excessive smoking and diluted oil in the crankcase. On a 6.2 GM I had a leaking injector and it caused a nasty ping that sounded like a lifter, I don't know if a leaking injector would also cause this on a Dodge? I bought a compression tester just for this. What do you recommend I begin with? Does the fuel distributor have an adjustment? I also have a three speed automatic that's run down and I'm pondering on wether I should repair the one I have or replace it with one that has an overdrive or even a manual if it's not too much trouble. One more thing...The temp gauge wasn't working, another guy replaced the gauge, I grouded the wire the goes to the sending unit located on the left rear of the cylinder head and had no change on the gauge so I replaced the sending unit, only to find out that there is a resistor within a wire about 6 inches long that connects to the sending unit that was open. I called Dodge for the resistor and they want to sell me the whole harness which sounds rediculous. Do you have any of these resistors or have access to the resistance value of this particular resistor? I like the truck and the engine, it's the first I will commit to work on and your help will be greatly appreciated. Thanks
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Answer
Fuel can only get into the oil in 2 places,the fuel injection pump or the lift pump on the side above the starter.Rich fuel mixture could be from someone playing with the pump for more power.Does it run good or miss a little?You could take the injectors to a pump shop for a check.They normally dont leak because it takes 5000 psi to open the injector.Black smoke is not enough air or too much fuel.If the stripes on the resistor are legible,go to Radio Shack for one.