Recently while coming to Branson, towing our 37' 5th wheel, after arriving at our RV park and registering, the truck wouldn't start. It is a 2003 2500 HD Duramax with 145,000 miles on it. We had it serviced the end of February, oil change, lube, fuel filter, replaced some transmission cooling hoses that were leaking, etc. The truck ran fine all the way down, about a 4 hr. trip. My husband primed it, still would fire, but wouldn't turn over (we have 2 new batteries). Finally, after priming it several more times, it started and we were able to get to our campsite. After it being shutdown for about an hour, we started it right up and have been driving it all week with no more issues. What could have caused it not to start in the first place. Never has done that before.