Odd Fuel Leak!!!

[Yaryan92]

Okay so i searched around and nobody else seems to have the same issue as me.. My trucks an 02 gmc 198k new injectors 9k ago. has a edge evo cs. boost valve straight piped. So anyway my fuel leak is weird is started when i moved to Co. on my way over it started leaking fuel my edge was on extreme. no fuel in oil but it was coming from the drivers side firewall valve cover. soaking the bottom of the truck. Still getting good mpg. So i got to Co. turned my edge down to performance. fuel leak stopped. no fuel in oil. nothing. recently i turned it back up to extreme. my leak came back. still no fuel in oil. no rough idle. still good mpg. but leaves a little puddle where i park. Could it be a high pressure line? Im so lost now. when i turn it down it stops. but as soon as i turn the edge back up it starts leaking again... PLEASE HELP!

 

[Hot COCOAL]

Cuz the engine fan pushes such a large volume of air, finding the point where a leak "actually" is can be difficult.

I wouldn't think by what you're describing you've got any injector issues, so I'd stop focusing/worrying about your injectors.

Every time you're "turning up" the tune, your also turning up your commanded and supplied fuel pressure, sounds t me like you've got a leaking fuel rail port, FRPRV (fuel rail pressure relief valve) or maybe an injector connection that's not all the way tight or maybe has a small piece of debris or a nic on the sealing surface between the hard line and injector

I'd start looking in the simple spots first...

To find it as quick as possible, I know that on my LBZ I can unplug the pressure regulator on the CP3 and then start the truck, and by doing that it will cause the CP3 to run at it's max pressure...
If you've got a leak on the high pressure side of the fuel system you'll be sure to find it doing this. Cuz some/most times a leak only presents itself under load when the CP3 is producing more than the pressure required at idle...

Good luck and

BE ABSOLUTELY CAUTIOUS WHEN INSPECTING FOR A FUEL LEAK ONTHE HIGH PRESSURE SIDE OF THE FUEL LINE!!!! At first stay back and away from the engine bay when you fire the truck up, your cp3 will be producing 22,000 PSI if the pressure regulator is unplugged,if you come in contact with that it will cut right through you and potentially kill you

 

[Yaryan92]

Ill do some searching and see if thats possible. Im on your side im thinkin something on the high pressure side. are the return lines high pressure? Thanks for the help. I wish i had a diesel black light!

 

[Hot COCOAL]

Ill do some searching and see if thats possible. Im on your side im thinkin something on the high pressure side. are the return lines high pressure? Thanks for the help. I wish i had a diesel black light!

No, the return lines are not a high pressure line and the individual lines coming off of each injector, from the CP3 and the rails are rubber fuel line...it's quite possible that one of them rotted although probably not likely...
And the fact that you're experiencing the leak when you're using more powerful tuning would lead me to look at the high pressure side of the system first

I believe there is a dye you can put into the fuel to help locate a leak, I have never used or seen it and I'm not sure what it's called but I'm pretty sure I've read about others using it

 

[clrussell]

My bet is high pressure line, had one start leaking on a truck about 20k after injectors. Line was rusted and corroded under the lower nut and finally rattled itself loose.

It was third one back passenger side, under fuel filter mount. Replaced it and it was good to go.. Now if they are remotely corroded they get replaced

 

[Yaryan92]

It seems like the leak is coming where the injector line goes though the valve cover?

 

[Yaryan92]

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[Yaryan92]

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[Yaryan92]

So if i pull the upper valve cover off what all is needed to put it back? o rings? gasket?

 

[clrussell]

Just take the line off and replace it if you can. It screws down to the injector. If it's not making oil it's just leaking externally.

Upper valve cover is just rtv gasket if I remember correct. So just clean it off and re apply.

You shouldn't need to pull the upper valve cover though.

 

[Bustedknuckles]

You dont need to take the valve cover off. Just loosen and re-tighten that line and tighten it like crazy. Unless its really corroded it should be fine.

 

[IdahoRob]

I can't see the pictures so;

LB7 injector main return line bolts to the head. The high pressure lines go through the valve cover and the individual injector return lines are all under the valve cover.

Bigger HP tunes may be increasing the fuel pressure, correct. This can cause leaking on the return side as the injector returns more fuel, esp. on a LB7.

I'd check the head where the return line banjo fitting/seal is.

 

[clrussell]

I can't see the pictures so;



LB7 injector main return line bolts to the head. The high pressure lines go through the valve cover and the individual injector return lines are all under the valve cover.



Bigger HP tunes may be increasing the fuel pressure, correct. This can cause leaking on the return side as the injector returns more fuel, esp. on a LB7.



I'd check the head where the return line banjo fitting/seal is.

Rob see if this picture works for you.

Wouldn't it make oil if a return line was leaking at the fitting into the head(inside the valve cover)? Or are you talking about the return fitting that's external to the head?

 

[IdahoRob]

ahh, thanks. Correct if the return line inside the valve cover was leaking then I agree there would be internal fuel. I was thinking it was the external return line on the head by reading his description.

The picture threw that whole thought process out the window. Sorry for muddying the thread.

 

[WolfLMM]

Check your high pressure lines! I had a leak on number 8. Removed line and cleaned and re installed! I didn't take anything else off. I'm almost positive that's your problem.

 

[Yaryan92]

Alright ill give that a try this weekend. hopefully it does. if not the guys at diesel day dreams said they diagnose it for free. but i cant get down there for two more weeks... ii wish i had a shop doin this in a apartment complex parking lot is pretty ghetto lol. Thanks for all the help.

 

[Yaryan92]

One more question about corrosion on the end of the line. A guy told me that if it is leaking around the seal it should be super clean because of the high pressure of the fuel would clean the end off? so if there is corrosion then its sealing good. His logic made sense. but Idk. Whats your opinions on that?

 

[Yaryan92]

anybody??

 

[clrussell]

Lost me there. I'll take a picture of a line when I get to work and try to explain it best I can.

Give me a couple hours I'm headed to the gym

 

[WolfLMM]

You lost me too, but corrosion on sealing surfaces is always bad. Line should be replaced if any signs of corrosion are present.