Filter code when heavy towing

[Heavy Metal]

Love my 2008 3500 GMC Duramax, but it has a problem that it's had for some time and getting worse. So far, only when towing a pretty good load, usually at speed, it occasionally throws a "change fuel filter" code and goes into limp mode. This is regardless of age of filter. On a recent "attempted" trip to Utah, headed across OK and TX, running about 70 against a strong headwind, it threw the code probably 20+ times. I only had one extra filter, so after that, literally every 1.5 to 10 miles, I would pull over, reprime the fuel pump, wait a few minutes, reset the warning light, and go. Gave up after 400 miles. Turned around , headed back, it only threw code three times, and has not done so in over a thousand miles of non-towing driving. It started doing this around 190k and now truck has 225k miles, run opti-lube every tank, run Racor Filter. Any help would be appreciated, but I don't want to spend a ton of money on some fancy fuel system. I'm thinking about ordering the fuel head rebuild kit but would like some input on any other potential issues. BTW, had a code check run on it. I have no idea if this makes any sense, but the mechanic told me a sensor that tells the engine how cold it is (in regard to fuel mix?) was telling the engine it was 22* below zero, but again, I've had no issues in 1000 miles of commuting...

[Mike D]

Do you know what code it was throwing besides change fuel filter?
Also are there any modifications done to the truck or is it all stock?


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[Heavy Metal]

Truck is bone stock. I do not know specifically which code but can probably find out from Mechanic.

[novaman64]

Codes would definately help. But a couple things to check would be:
-check the factory fuel line, some of then can have a kink up near the engine
-check the rubber hoses, if they are aging and overly soft, they could be collapsing and causing low pressure

[Heavy Metal]

Mechanic does not have records of codes unfortunately. I can def check out the hoses but probably need to get it code checked again. I've been told the filter heads can be a problem on these, and of course fuel rails are a concern. I'll post back when I get the codes. Thanks all.

[Mike D]

Mechanic does not have records of codes unfortunately. I can def check out the hoses but probably need to get it code checked again. I've been told the filter heads can be a problem on these, and of course fuel rails are a concern. I'll post back when I get the codes. Thanks all.

Yes the filter heads and correct fuel filter is a must. We always recommend and Airdog fuel system for all Duramax owners. Using an Airdog will keep injectors, pump, and fuel system clean and happy. It will also keep the trucks fuel system primed because it eliminates the vacuum and used low pressure to prime. Let us know what you find out. More than likely you will not see an issue until you start pulling a load again. This is when the fuel pressure commanded by the ECM is commanded elevated and problems show up.

[Heavy Metal]

So I had the opportunity to do a little towing yesterday, 90 degrees plus with humidity to match. I was intentionally light on the pedal as I was helping a buddy get a broke truck home, but we came up to a big grade and sure enough, right at the top of the hill, "Engine Power Reduced"... Change Fuel Filter. Grrr. So, I'll get the codes read shortly. If it's fuel system and I need to do an aftermarket upgrade, I'm looking at the Air Dog and the FASS. My friends (mostly Cummins) swear by the FASS, but a lot of Chevy guys seem to like the A-Dog. I just want this problem to go away. Any final advice?

[Heavy Metal]

Got the codes read this weekend. Low fuel rail pressure. Since the issue only occurs under duress towing (heat/grade/load) I'm thinking the CP3 may be involved, but i am committed to upgrading to a FASS or Airdog. In your opinion, would the additional pressure from one of these systems decrease load on the CP3 significantly?

[Mike D]

The AirDog is a much better product for the Duramax. We sell and install both. However if asked for a
Recommendation it's always Airdog.
What year is your truck? How old is the fuel filter housing and what fuel filter you running?

[Heavy Metal]

Truck is 2008., 240k miles. Filter housing about 5 years old. Filter is Racor.

[Mike D]

Truck is 2008., 240k miles. Filter housing about 5 years old. Filter is Racor.

Ok sounds like your doing good maintenance. I would do an AirDog asap. Hopefully your injectors are performing good. The LMM injectors are known to get week after a couple hundred thousand miles.


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[Heavy Metal]

Thanks Mike. I'll order this week.

[DMAXDR]

Before just replacing the CP3 ,I would find a competent shop to preform an enhanced fuel return rate test to all 8 fuel injectors. There are cases where the injectors will have high return rates when hot and around 100mpa fuel pressure. Which is where they operate under a load. The enhanced test is to simulate this while individually testing each injector. It would save you guess work and multiple repairs.