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GM Tech (Cam)
GM Tech (Cam), GMC Mechanic
Category: GM
Satisfied Customers: 29427
Experience:  GM Grand Master Technician 2007. 14 years experience.
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2006 GMC: duramax..Engine power reduced light comes..pulling..hill

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2006 GMC 3500 with a duramax. Engine power reduced light comes on under a heavy load when pulling up hill resets on its own after about 10 miles of lesser demand on the motor. Replaced the fuel and air filters with no difference. I have taken it to the dealership and they are getting a high fuel temp reading. Fuel temp gage tests normal and fuel cooling radiator was washed out ,all injectors test normal. Dealership is going to replace the fuel cooling radiator for $500.00. I am having a hard time believing that this is the problem. I have a buddy that thinks the fuel pump may not be keeping up with the demand therefore creating a vacuum on the system which in turn could create the fuel heating scenario. Any ideas.
Welcome. I agree with your friend, partly. What I see happening on these is the injectors start to return far too much fuel to the tank, and this gets worse when hot which causes more return flow to a point that the pump cannot keep up to the system. The test I perform to confirm this is to test the return flow rate from each injector when it is hot. Most dealers don't really want to do this test because it takes a bit to set up, but you cannot accurately test with out this test.
GM Tech (Cam) and 2 other GM Specialists are ready to help you
Customer: replied 7 years ago.
So are you leaning toward the pump or injectors?
More to the injectors and very doubtful of the injectors. How heavy of a trailer do you tow?
Customer: replied 7 years ago.

Fully loaded with horses I'd say somewhere around 12000 lbs but i can get it to throw the power light even with the trailer unloaded on not much of an incline. I am just very skeptical of the dealership wanting to change the fuel cooling radiator because in my way of thinking since it is not leaking fuel that if this were the problem it would surely present itself during normal driving conditions in stop and go traffic as the weather is hovering around 100 degrees here. In your last reply i think you meant to say that you are doubtful of the pump is that right?

Thank you very much for the insight.

I have only ever changed one cooler, and it was because it was leaking.

Yes, I do not suspect the pump.