Hello all I am completely new to posting but I have been reading for a month or so. I will post as much information as I can recall.

The problem is that the 2004 ram 3500 cummins will not start below 65 degrees unless the block heater is plugged in or I hit it with ether. Once it has started it will run great until it has sat long enough to cold soak. I have ran thro the air intake heater troubleshooting and even replaced the temp sensor. I have tricked the relay with a 9v battery and it still will not start. I have change fuel filters, air filters and both batteries.

I recently took it to a local diesel shop because I started to loose faith in my own troubleshooting. I informed them of all of my previous efforts. I asked that they look into the lift pump. The shop said this was not my problem. They requested that I approve $450 in additional troubleshooting to check the fuel injectors. I do understand that a small crack in an injector(s) could cause the fuel to bleed back and prevent me from getting the required pressure (5K psi I believe). So I took the truck back and started looking for tests I can run myself.

I have ordered the Miller line block tool. Having read many other post and talking with a person at Geno's garage my understanding is that I can block each (excuse my terminology if it is incorrect)output line on the common rail 1 at a time. My understanding is that if I block one off and I am able to start the truck it mean that the associated injector is cracked for worn.

My question is: Do I simply leave the fuel feed line to the injector disconnected with the output on the common rail pugged when I try and start the truck? Will this cause any damage? Can the fuel pressure back feed through the injector to the loose line? Am I missing anything?

If I find a back injector it is my intent to R&R it myself... Any thought?

One other pertinent fact about my fuel system is that I run aircraft fuel (jet a or the MIL cert version JP-8) I add stanodyne for additional lube.

Any help is greatly appreciated

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Couple additional notes

5.9L cummins

I live in Denver and the problem started in September at elk camp I did have to replace a surp belt that was coming apart at that time. Also I am at 137k miles. No mods other than the 5th wheel towing package.