I have a '93 Dodge 5.9 Cummins Pickup. It has 208000 miles on it. I have kept it maintained by the book. This Winter, after I had plugged in the block heater/transmission pan heater/oil pan Heater, it started fine. After sitting for a while in cold weather, it failed to start. It needed a jump to start it. I thought it was the battery. I had Napa test the battery and they said that it was fine. I plugged in the truck and it started the next morning just fine. Again while it was cold it needed a jump to start. I took it to the local Cummins shop and they found a short to the fuel pump. They fixed it. It started just fine in their garage. It started for me when I picked it up after it sat outside for about 2 hours in the cold. I got it home and it started just fine the next morning (after being plugged in all night), but failed to start after sitting in the cold. It started cold with a jump.

I let it sit until the snow melted to work on it again. I checked the starter
circuit. From the battery to the starter, the positive cable had a crack in the connector to the battery. I decided to replace the whole cable. I charged the battery and tried to start it. No start. I plugged it in (the ambient temp was 40 F, it should have started) and when it was hot it started fine. I can start it hot and as long as I don't let it sit more than an hour or hour and
a half, it starts just fine.

Does anyone have any ideas?

 

When it won't start cold, does it crank slow?

 

When it is cold, it cranks slow and after about 8 slow cranks, it starts clicking and cranking, clicking and cranking for about 15 times before it runs down the battery to where it doesn't turn over.

 

Gotta be a starting system issue. Check the voltage drop on both cables. How did NAPA test the battery? If they used one of those handheld boxes their test doesn't mean squat. Those boxes can't put enough load on a big battery like ours to tell. Check the battery voltage during cranking, that will tell you if it's any good. If it gets below 10 volts it's trash.