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Duramax Second Generation: 2004.5-2005 (LLY) Discuss the second generation (2004.5-2005 LLY) of the 6.6L Duramax diesel engine & associated components. 2006 LLY engine discussion belongs in Third Generation forum due to the differences of the 2006 LLY and the 2004.5-2005 LLY. Engine related discussion ONLY.

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Old 07-22-2019, 01:30 PM  
1991 K1500
Freeze Plug
Join Date: Jul 2006
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Leak from CP3 high pressure line?

Hi there

I've got a Duramax converted Durakon - chasing down one last leak.

Quick run down - installed a stage 0/stage 1 or somewhere in between built LLY/LBZ motor into my GM Suv conversion.

CP3 was new when motor was installed and bought from SoCal - has about 4k miles on the motor/CP3

The line/area is wet at the fitting on CP3 pump --- so its the line that goes from the CP3 pump to the drivers side fuel rail - really short line - -

It's wet at the base of the fitting -- I dont know if that line was overtorqued when it was installed - whether the line is slightly "boogered" up and it just wont seal correctly or if the CP3 had a bad fitting and it's leaking there - fuel gets in the valley and drains during driving and drips down the back of the bellhousing -

I can visibly see the fuel is wet at this connection between the CP3 and the Fuel line from the fitting on the CP3 to the fuel rail.

Would I be best to just replace the fuel line from the CP3 to the Fuel rail and see if that solves it? I've already tore apart the accessories to get to the fitting to try tightening it a bit (tightened it a little) but it didnt solve the issue. Biggest pain is reinstalling the power steering pump by yourself - rest of it all came apart easy - there just is no simple way to access this area of the motor.

How do i know if it's a bad fuel line or if there is an issue with the fitting on the CP3 -- the fuel line is around $70 if I recall.

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Old 07-23-2019, 11:25 AM  
Sparkplug Hunter
Join Date: Apr 2017
Posts: 132
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You could try loosening both sides of the line and let it go back to neutral position. Line may be crooked a bit. Tighten both ends gradually with a crows foot line wrench and use the actual torque spec. Its higher than you would think.

i dont remember taking off the power steering pump? I just did the CP3 not too long ago too.

2004.5 LLY CCSB, Headgaskets and Studs DONE!, EFI by Idaho Rob, EDGE CST Monitor, Purring on Homebrew BioDiesel for the last 15,000mi.
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Old 07-24-2019, 08:49 AM  
Diesel Pro
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Join Date: Jun 2016
Posts: 2,312
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Michigan Oil Burners Member

97321372 Hose, Fuel Return (From Pump To Connector Pipe) $29.15
97351316 Clamp, Fuel Hose $1.27

Last edited by Rvn4me; 07-24-2019 at 08:54 AM.
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