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Chevy/GMC Duramax 04.5-05 LLY Discussion of Chevy and GMC Trucks with LLY Duramax Turbo Diesel Engines

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  #1  
Old 01-31-2013, 12:37 PM
Newbie

   

Default LLY Cranks fast, wont start when Hot

This 05 GMC Duramax, driven 150,000 miles hard, use lots of offroad fuel, always changing the fuel filter, older Edge with Attitude, big intake, 4" Turbo back exhaust, new batteries.....

Starts best in the morning, not instantly, but within 3-4 seconds.

I drive 1.5 hrs to work, and it wont restart without starter fluid which I hate to use and avoid at all costs.

Seems to start easiest when cold. My suspicion is, hopefully, a bad flex line that may be collapsing.

Anyone have any experience with a problem like this??

I am not very familiar with diesel/duramax tech.

Thanks!!!!!
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  #2  
Old 01-31-2013, 07:02 PM
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Check your fuel filter(s)? I had a loose one before up front and it cranked but no start. I have heard of fuel pump housings cracking to form air in the system on these LLY's. Do you have a lift pump? Your CP3 may be getting tired. It is for sure a fuel issue based on what you wrote.
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  #3  
Old 02-01-2013, 07:31 AM
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Fresh, tight filter. I installed clear fuel line entering and exiting filter housing. The line exiting to the fuel control module doesn't stay "full" there is air that will not go away. Yet, the truck runs perfect. Drive perfect. Full power thru 3500 RPM. I will drive it to work today and see if this starting problem persists. I found someone who has a computer diagnosis program that may be able to check the fuel system components.
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  #4  
Old 02-02-2013, 10:41 AM
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So i removed the plastic cap on the fuel line behind the alternator. I guess thats where I test rail pressure? We put a hose on it, filled it with fuel, and pushed the pin with a rod... it kept taking fuel. We added about 2 cups. Seems that portion of the fuel system is starved (immediately after the fuel module behind alternator). Kept turning engine over with a sprits of starter fluid, finally started, ran perfect. Having a hard time locating a shop with equipment to test/service this motor.
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  #5  
Old 02-08-2013, 07:51 AM
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So some module or something is not functioning when truck is operating temp.

If I open the hood to cool it quicker, after running it, it starts right up after a couple minutes. If hood remains closed, it takes considerable time to want to start again.
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  #6  
Old 03-06-2013, 04:53 PM
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Status: Cummin Stroke on This DURAMAX!

   

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Ive heard of people having their truck start fine when it's cold but when it's warm it doesn't want to start. It's most likely air getting into your fuel system (fuel rail, pump, filter housing) or a bad injector(s). Any air that you have in your fuel system will cause hard or no starts.
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  #7  
Old 03-18-2013, 01:01 PM
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Sounds like you have got yourself a "hot start" problem. I'm sure you figured that out. I haven't had that before on a duramax... On '04-'07 powerstrokes that exact problem is caused by a bad fuel pressure sensor lying to the computer. Try and google LLY hot start problems.

c-tane's Sig:'05 Chevy 2500 HD Crew Cab LLY 4x4 with modified airbox, AFE intake elbow, PPE boost controller, Finger Stick, Duramilage programming, Banks 4" exgaust, CST 6" lift, and 35" Rubber.'05 Ford Excursion 6.0 PSD 4x4; Zoodad air inlet mod, Bullet Proofed EGR, Blue Spring, 6.4 Bango Bolts, STC fitting upgrade, Original Headgaskets/Bolts, SCT programmed by, Eric, and Scan Gauge II with fuel pressure fitting.
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  #8  
Old 03-18-2013, 03:03 PM
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you need to check with a scan tool what your rail press is while cranking, could be a weak fuel press relief valve, bad injector or two, something along those lines. deff. need to get a hold of a scan tool.

---AutoMerged DoublePost---

Originally Posted by eidolonusa View Post
So i removed the plastic cap on the fuel line behind the alternator. I guess thats where I test rail pressure? We put a hose on it, filled it with fuel, and pushed the pin with a rod... it kept taking fuel. We added about 2 cups. Seems that portion of the fuel system is starved (immediately after the fuel module behind alternator). Kept turning engine over with a sprits of starter fluid, finally started, ran perfect. Having a hard time locating a shop with equipment to test/service this motor.
That port is where you measure filter/system restriction. Its under vaccum. dmax doesnt use a lift pump in truck applications it relys on vaccum supplied by the cp3.

Last edited by MillerBoyzDiesel; 03-18-2013 at 03:03 PM.. Reason: Automerged Doublepost
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