Duramax low fuel pressure??

[Houndoc]

Had a great week at Lake Powell, not crowded and the new boat was great.
But, as we pulled out of Bullfrog to start the journey home had the check engine light on my truck (2008 GMC with 6.6L Duramax) come one and 'engine power reduced' message came on (as if I couldn't tell by the 35mph climb.)
Limped back to Bullfrog and their boat shop was able to run codes, showing 'reduced fuel pressure' but couldn't do anything beside reset the codes.

Since my daughter had to catch a flight the next day for a 1 month internship in Morocco we couldn't risk getting stranded so made the decision to park the boat and head for home with the lighter load. Made it no problem (and she landed in Rabat today.) Unfortunately now unable to get the truck to not run well, including running around yesterday with my horse trailer, trying to work it harder.

We had replaced the fuel filters in May, so not likely the problem.

Thoughts as to possible causes?

The other issue is do I dare use it to go get the boat sometime next week if I can't get it figured out and fixed.

 

[ID Bronco]

I'd get another truck to pull the boat home and then pull it around to diagnose closer to home if it were me.

 

[Trate D]

I would look into a lift pump system. These trucks solely rely on the injection pump to siphon fuel from the tank all the way up to the pump. Some times under load it can’t keep up with demand. A lift pump provides consistent pressure which usually alleviates this issue. I run the fass fuel titanium on mine and have never had any issues since install.

 

[Rot Box]

Hard to say on a truck that does not have a lift pump. Could be a low fuel rail psi x2 (which is what the computer monitors if I’m not mistaken)… if that’s the case I think the CP3 could be on its way out. Would need a good scanner to know for sure I’m just not familiar with the Duramax enough to know which direction I’d head from here.

If it were me and I was you (spending your money) I’d like to have a nice aftermarket lift pump and gauge to know for sure that my CP3 was being fed enough fuel. But all things being equal and squared away it should pull enough fuel to feed itself…

I’m not much help but I’d find a good scanner (I use FORScan lite with Bluetooth to my phone) and see what it’s doing. Hope you get it sorted. I agree might be best to tow back with something else until you get it figured out.