Won't start at altitude?

[dmizesr]

I have a 2022 Ram 2500. It has the Tradesman package and the 6.7 Cummins Diesel. I live in my RV and move from Phoenix to Prescott and back depending on the weather. I bought this truck in October of 2024. It currently has just over 42,000 miles. It's a salvage title. It was stolen, vandalized, recovered and totaled by the insurance company. The truck is cherry, but the vandals put gas in it. The dealer I purchased it from (allegedly) flushed the entire fuel system, replaced the filters and then, ultimately, replaced the fuel pump. Here's the issue. When I have the truck in Phoenix it runs like a dream. The grid heater comes on before starting about 30% of the time since it's seldom "cold" in Phoenix. I used the truck 3 days ago to pull my RV (11K pounds) up to Prescott, no problems. But, when the truck is in Prescott, the truck will not start on a regular basis. The grid heater comes on, it's warms up for 8-10 seconds, and then it just cranks. So the truck runs like a dream in Phoenix, and won't start at least half of the time in Prescott. The difference is, the elevation in Phoenix is about 1,000 feet and in Prescott is 5,300 feet. Also, it is routinely 20 degrees colder in Prescott than Phoenix. Those are the only differences in the environment for the truck.

Any suggestions/help greatly appreciated.

 

[06 Dodge]

Have you checked for codes, that would be the first thing I would check.... Gas is killer to a modern diesel fuel system so it would be a good idea to check injectors, are you 100% sure they replaced the HPFP and not the life pump in the tank? I would also want to be sure the correct OEM air & fuel filters are being used an not aftermarket... As for the grid heater it will come on any time the air temp sensor reads the temp under 66 degrees...

 

[GTyankee]

Try this, mostly to eliminate a possible issue

• Key on.
• Let the “Wait to Start” lamp turn off.
• Turn the ignition off for 5 seconds.
• Key back on.
• Let the “Wait to Start” lamp turn off.
• Start the engine.