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Discussion Starter · #1 ·
Hi Folks,
I've been visiting the site past few months ever since getting my 04 CC 2500HD and have found a lot of useful info on here about upkeep and mods to these trucks and have been planning on ways to make my truck last for a good while. I am not new to diesels and have wrenched on a few fords and 6.5 GMs in the past but this is my first Duramax and I absolutely love it!

I got a problem 2 weeks ago when I went to top off my tank at a gas station right after a heavy down pour that flooded the area not even thinking. I get a bout ten gallons of diesel to top off. About a mile later my engine starts to stutter intermittently. I continue on and make it home. The next day it dies out about a half mile from home. Now my gauges don't work along with the water in fuel light(one of the things I gotta get fixed). I go to open the water drain from the fuel filter and nothing but water streams out. I pump the primer to try and get it all out and I get about a quart and a half maybe more out of the filter. I finally get her started and drive back home. Empty out the tank and theres a good three quarter gallon of water in there and the diesel is very cloudy. Change the fuel filter put clean diesel and go to start her up and it is loud and missing with slight smoke. Loud like a powerstroke with a miss. when I press the accelerator it does not feel like its missing but there is reduced power.

Now I noticed when I got the truck there was a slight diesel leak that came from the rear of the block on the passenger side. trailing down the head then to the block. After clearing out the water in the tank the fuel is now almost gushing out the rear of the block down the sides. I've been searching the internet for any similar problems of being loud and missing but no luck. I've started tearing down to get to the CP3 but looks like it might have already been replaced.

My question is:
1. Could there still be water in the fuel filter or air in the lines causing it to run this way? or
2. would the miss and loud firing be related to the leak. or
3. bad pump and/or injectors

My train of thought is to find the leak and fix it first but the more I tear it down I fear I'll have to replace a lot of parts in the process.

I would appreciate any and all input. :help
 

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Gushing?

Fix the leak. Rule out loss of fuel pressure (not) feeding the injectors.
 

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Discussion Starter · #4 ·
Well, I fixed the leak and got it fired up plugged in scanner and go P0088A and P0089A.
Fuel rail pressure too high and Fuel regulator performance. Still running rough. My actual fuel rail pressure is up at about 25,000 psi and desired is 4,300 psi. this is at idle. Before firing it up after the water was cleaned out of the tank I replaced the OEM fuel filter. Could I have installed it wrong? or do I have a bad fpr?
 

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Well, I fixed the leak and got it fired up plugged in scanner and go P0088A and P0089A.
Fuel rail pressure too high and Fuel regulator performance. Still running rough. My actual fuel rail pressure is up at about 25,000 psi and desired is 4,300 psi. this is at idle. Before firing it up after the water was cleaned out of the tank I replaced the OEM fuel filter. Could I have installed it wrong? or do I have a bad fpr?

im fairly certain that my sister in law could replace a duramax fuel filter with out breaking a nail or spilling her pumpkin spice late, so im confident that you put it on right. my money is on the FPR like you said. if your getting 25K the CP3 is working, the regulator makes sense as the problem.
 

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Discussion Starter · #6 ·
ok question. will the cummins fuel pressure regulators work in the LB7 CP3? just curious cause I have 2 laying around.
 

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Discussion Starter · #7 ·
Something I just noticed today. morning I went to start it up and started and sounded normal then it stalled. I'm guessing I have a leak that caused the fuel to dry up over night. would a bad fpr cause the engine to loose prime overnight?
 

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Something I just noticed today. morning I went to start it up and started and sounded normal then it stalled. I'm guessing I have a leak that caused the fuel to dry up over night. would a bad fpr cause the engine to loose prime overnight?
a bad filter head, or a double gasket on the filter would. as far as the cummins parts, i would be very surprised if they interchanged, but i dont have the experience to tell you they wont for sure.
 

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Discussion Starter · #9 ·
Thanks J83, I swapped in the Cummins FPR and it solved the High Rail Pressure problem. but I am loosing prime now. if I leave it for an hour then I loose prime. I also have a slight lope if you would call it that. How can a filter head go bad? Truck is all stock and while changing the FPR I ditched all the egr hoses and sensors.
 

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Common for the filter head seals to dry up/shrink from the engine heat. 100s of posts of the filter head problem.

Start with replacing the seals-- and don't forget the o-ring at the heater connection. Seal kit is available from the Forum Supporting Vendors-- or check your local auto part store-- Dorman Primer Seal Kit.
 

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... I also have a slight lope if you would call it that. How can a filter head go bad?
Inner seals wear. More than a common issue since the switch to ULSD.
Also can cause a lope at idle.
 
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