hot diesel fuel

First get a code reader -cheap and something good to have. Once you know the code research causes on dieselplace.com. Some good suggestions about checking fuel cooler - small radiator under truck in front of driver side rear wheel. Clean it if plugged with mud. Then also possible are collapsed lines.

It's not that uncommon. It happens much easier with less diesel in your tank. If it's hot out on a long trip try to keep your tank half full or more. Or add abother auxillary fuel cooler if it occurs regularly. I think I remember it also happening when your stock lift pump gets tired and builds up more heat than it should.

There is a fuel cooler under the truck. It cools all the excess fuel as it returns to the tank. Maybe it is dirty.

Moved from Forum Technical Support

Go to the Duramax forum and ask your question. I would doubt the dealers diagnosis is accurate. Their computer may say that is the problem but the computer is just going by the sensors in the engine.

For example The truck believes you have 0 percent fuel filter life remaining. This is often triggered by a reduction in injector rail pressure. That can be caused by a dirty filter or when under load, in heat, (like you describe) the rubber fuel lines will collapse. The Duramax does not have a fuel pump to maintain positive pressure in the hose. One fix is to replace all rubber with better fuel lines or get a lift pump added.

The point is that the computer does not always know the root problem.

One dealer tried to sell me $10,000 worth of injectors when what I needed was the new hoses or a lift pump. The dealer said they had never heard of that problem and yet there is a GM tech bulletin on the issue.

Cummins has a fuel heater... Makes me wonder if the Duramax also has a fuel heater, if the relay for the heater stuck closed (why was it even activated), and if it is even capable of heating the fuel to that temperature. Or the fuel temp sensor flaked out briefly from a loose connection.