Lbz leaking, grrrr!

[RidinHigh99]

Hey guys, I'm fairly new to this forum and to actually having a duramax. I bought an 07 lbz with 105k on it. Efi live, dsp 5 with cobalt gauges. S and b intake. Last week I was throwing a p0087 code for low fuel rail pressure. I bought a scan gauge 2 and cleared the code and it hasn't reappeared in 150 miles. What is weird is that I am leaking fuel down the drivers side, from what appears to be the back part of the motor. It's hard to see because of the glow plug controller. It drips from the bottom of the bellhousing onto the ground. Does anybody have any suggestions as to what it could be? The two lines that go from the tank then turn up into the motor and turn into the flex lines are not leaking either. Could it be a leaky return O ring on the back of my cp3? I had a buddy rev it while i looked under the hood and couldn't see shit. Its defiately not the return lines, they're all 100% dry. Could it be a seal in the farthest back injector? The tag, is the tag that usually goes on the back of the head on drivers side. was soaked in diesel… Any help?

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[NC-smokinlmm]

Check the soft lines feeding the cp3 off the filter head. Generally when there is fuel dripping down the back of the motor it is coming from the cp3 area and running thru the valley out the back...

 

[BobbyBDirtyMax]

It could be a blown or malfunctioning fuel pressure relief valve in the back of the drivers side fuel rail too

 

[RidinHigh99]

The only problem is the passenger side is dry as can be, while just the drivers side back 1/4 of the motor is wet. granted then it drips down the bell housing…

Could a malfunctioning fprv cause it to leak this much though?

 

[testdrive]

If I understand this correctly, you think the leak is from on top of the valve cover near the rear injector... Rule of thumb is if the leak is inside the confines of the valley diesel will pool in the valley and make it way down from the back of the engine and then the bell housing. You should be able to see a pool if you look carefully. Your picture indicates that the diesel is coming from around the injector and then down to the bell housing area.
Take a pump sprayer with a concentrated dish washing soap and flood the valley and then a garden hose and carefully wash out fully. For checking a fitting for leak, wined a second of paper towel around the fitting and run the engine.

 

[NC-smokinlmm]

Take a look a the fuel supply lines on the drivers side, they are directly above where the leak apoears to eminate from. There are quick connects that go from hard to soft lines that maybe leaking...

 

[RidinHigh99]

I had my buddy hold it at a solid rev at 3k/3500 rpm and couldn't get anything to spew fuel or such.

 

[x MadMAX DIESEL]

Since that tag is wet..... I think its either a soft u shape return line leaking, loose injector fitting, or the fprv isnt tight. Im guessing the latter 2 since you had a low pressure code on in the injection system.

 

[RidinHigh99]

what do you mean by a loose injector fitting? Fprv is tight i tried to get to it with a 18mm wrench and couldn't tighten it anymore..

 

[testdrive]

Have you thought about using dye? Check out this post and follow the links.
Post #11

 

[x MadMAX DIESEL]

Flare fitting on the hard injector lines. Either at the rail, or on the injector.

 

[x MadMAX DIESEL]

If it was me (im not telling you to try this) i would unplug the regulator on the cp3 to habe it go wide open. Watch carefully from as far a distance as you can and see if you notice anything you can hone in on later with it plugged back in. Careful of where you put your hands etc as high pressure leaks can go through skin

 

[RidinHigh99]

That would sketch me out mad diesel. I don't wanna blow my cp3 or any lines off that. I think I'm going to try the dye method, seems like the easiest way to track it down… I booked an appt at the diesel shop by me for friday incase i cannot find out what it is with the dye

 

[clean06]

I had the exact same thing happening as you described above it. it turned out to be short rubber line for return was leaking at cp3 it leaked enough to fill valley and run down bell housing

 

[TLKDRTYLLY]

The whole underside of my truck over the months has been covered in diesel fuel, starting to eat the coating off my frame. I cannot find the leak anywhere. FPRV is tight, Ported rail fitting is right, injector areas are dry, but the valley is wet. So I'm on the same boat as you man. Let me know what you found, I'm gonna check out those soft lines from the filter head on Tuesday.

 

[Hot COCOAL]

I had a fuel leak that left a similar "evidence" trail and was incredibly difficult to locate. I got a sweet bit of advice from sweetdiesel (Simon) and found the leak in seconds (after 2 weeks of trying) by unplugging the regulator

http://www.duramaxdiesels.com/forum/showthread.php?p=730492&highlight=Fuel+leak#post730492

Info in Post 10

Unplug the regulator and wrap all the suspect feul connections with paper towels, stuff em tight, wrap and tape them in place, whatever you have to do to keep them where ya want (I just stuffed em in there tight). Then fire up the truck for 15-30sec and keep away from the engine bay while it's running, possibly even lower the hood, just be safe and use caution cuz unplugging the fuel pressure regulator causes the CP3 to run max pressure (the truck will lope very heavily, don't worry it's normal) Turn the truck off after that short run time and inspect your paper towels.

This is how I found my leak, as it turned out, my leak was from the front of the rail at the rail fitting. Because the engine is tilted toward the firewall and the fan draws tremendous amount of air through the engine bay pushing the leaked fuel to the back of the engine I thought my leak was at the FRPRV, but it wasn't.

 

[x MadMAX DIESEL]

I shaped return hose off the rail?

 

[RidinHigh99]

I have the exact same leak. It's on the back of the cp3. The return line I believe has an O ring in the union, and the o ring is known to sometimes go bad. As long as she still gets up to rail pressure I ain't taking all that bs off just for a little few drops of diesel


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[RidinHigh99]

Did you end up finding the problem?


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