Question: High pressure fuel leak.

Fingers

Fingers

Village Idiot
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Apr 1, 2008
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Since installing the high flow injectors on my truck last year, I have had a high pressure fuel leak somewhere. I just can't find the darn thing.

I have reseated everything at least twice. No Joy.

I have dyed the fuel with UV dye and found the whole top of both heads lit up with UV marker. The darn fuel is atomizing into a fine fine mist.

After a hard pull, if I shut down right away and pop the hood I have fuel mist coming up off the engine, but not from any specific spot! :(

I am game on any suggestions on how to isolate the leak. I have a deep down feeling the problem is at least one cracked injector housing. I just wish I could isolate which housing(s).
 
McRat

McRat

Diesel Hotrodder
Aug 2, 2006
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When I cracked an injector, it got just that cylinder bank wet.

You can run your rails at max pressure by unplugging the CP3, then use both eyes, and a mech stethoscope to isolate it.
 
mytmousemalibu

mytmousemalibu

Cut your ride, sissy!
Apr 12, 2008
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Welcome to my world:rofl: The one thing i hate about LB7's and a problem ive spent chasing for along time, well injection troubles anyhow. What i would try is to get the engine real clean and free of diesel/dye. Now wrap and snuggly tape clean paper towels around injection line ends on the rails and the injectors. If one has a hi psi leak in the form of vapor or real fine mist, this might find it? U'll just hafta isolate the papar towel that lights up with UV dye the most? Dont forget the feed lines from the CP3, junction block and sensors too. I once left my feed line on the pump just a touch loose and it soaked my engine bay in diesel. Good luck, hope that might help!
 
Fingers

Fingers

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McRat said:
When I cracked an injector, it got just that cylinder bank wet.

You can run your rails at max pressure by unplugging the CP3, then use both eyes, and a mech stethoscope to isolate it.
Click to expand...

That's a plan. This only seems to leak at high rail pressure.
 
minisub

minisub

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Sep 11, 2006
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McRat said:
...
You can run your rails at max pressure by unplugging the CP3, then use both eyes, and a mech stethoscope to isolate it.
Click to expand...

Or just break out the black lights again and keep using the dye?

Just look for the little glowing geyser?
 
super diesel

super diesel

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May 14, 2007
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Wonder if the inject line or inject has a bad seat. I mean, where the hard lines screw onto the inject or the rails? I had one that got a little piece of crud between it and the seating surface and made a small impression in the line seat. It never sealed right and leaked at only the highest pressures. I wish you luck with this one my friend and I'm not envious of that delema.
 
Fingers

Fingers

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Well, programmed max PSI at idle and looked under the hood.

3 of the 8 are leaking. The fittings themselves are not leaking. It is either cracked bodies or the nozzle/body seal since it seems to be coming up from deep in the well.

:(


Thanks for the suggestions.
 
mytmousemalibu

mytmousemalibu

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Hey buddie you might be lucky, i had 2 loose nozzle caps on mine the 1st time i tore it apart. Apperantlly that might be a more common problem? Also, dunno if you know of this or not but check the little ball below in the hole below the solinoid caps, it should be seated down in the hole a bit, if its pushed out against the cap that inj is done.
 
minisub

minisub

6-5/6-6;Whatever It Takes
Sep 11, 2006
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Fingers said:
...3 of the 8 are leaking. ...
Click to expand...

That stinks. At least the diagnosis didn't involve strapping me to a chair on the front bumper with my head under the hood while we went for a ride...;)

Want to borrow mine for a bit while you get the ones on the installed motor honed so the swap is a one-time deal?

Be a good excuse for me to finally drill the damn hole in the bed and get the G/N hitch installed...:D
 
TheBac

TheBac

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Apr 19, 2008
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minisub said:
That stinks. At least the diagnosis didn't involve strapping me to a chair on the front bumper with my head under the hood while we went for a ride...;)

Want to borrow mine for a bit while you get the ones on the installed motor honed so the swap is a one-time deal?

Be a good excuse for me to finally drill the damn hole in the bed and get the G/N hitch installed...:D
Click to expand...

Ya know whats funny? I can visualize you two doing that very thing. :rofl::rofl::rofl:

Good Luck on the fix, Jon.
 
Last edited:
bullfrogjohnson

bullfrogjohnson

Big Girl!
Nov 20, 2006
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At work when we deal with HP leaks we use a piece of cardboard and move it around the suspect area to find the leaks because there would be nothing worse than HP liquid being injected into your hand
 
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