It only happens when I have a heavy trailer going up a steep hill. When the truck is at normal operating temperature, the truck goes into LIMP mode, the engine light comes on and throws the code for "Large Fuel Leak Detected". Once I turn the truck off, the engine light goes off and the truck drives normally until under heavy load again. If anyone has any ideas as to what may be causing the problem - please contact me. Thanks! (The truck has 219000 miles)

 

Fill out your signature so we know what mods you have.

What code are you getting?

 

It is possibly fuel pressure relief valve. Check your rail pressure at WOT.

 

What code is it exactly?

and yes what mods have been done to the truck

 

That would be my guess with what you have told us.

 

Whats happening is that your rail pressure is falling off to a level below what is necessary to continue producing power. First things first, when was the last time you changed your fuel filter. The filters on a DMAX typically start plugging up at about 15K and you will start loosing power and throwing codes. Change your filter and see if that corrects the issue.
If not, you need to check your FPRV to see if it is popping off early and needs replacement. There is a test you can do by pulling your return line from the tank and measuring how much fuel you get over a 1 minute period of time. This will let you know if the valve is leaking or not. The next are to look at is the CP3. Let us know what you find and we'll point you in the right direction.

 

Whats up Greg!? Glad you found the time to get on here. these Duramax guys will get you straight in no time!

I brought this one here guys....

His truck is bone stock, That much I know.

 

The truck has 285/75/16 Nitto, all terrain on factory wheels, goose neck hitch, a linex bed liner and step bars. The fuel filter has approximately 9000 miles on it but I will try it to see if it makes a difference.

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And its an 2001

 

Even with only 9000 miles on the filter it is possible to get a bad batch of fuel and clog it in one tank.

 

wouldnt hurt to change the filter, but what was that code name P0XXX?