You guys are my last hope! I am working on an 05 LLY. Very hard starting. I have check the glow plugs and they are all good and working. I have primed the system and still no go. I put UV die in the fuel and the only leak I found was as the service port which I replaced. When the truck starts it runs great! The truck does smoke pretty good when you get on it. It had the injectors replaced last year and they balance test out great. I installed a clear fuel filter in the feed line after the filter and noticed it was sucking air. So I by-passed the filter head completly and i am getting a few bubbles here and there but far less. So then I by-passed the fuel lines all together and hooked the fuel rail to a 5 gallon can and let it gravity feed the fuel. I purged the air out at the survice port and the truck will still not fire on its own. I know its a NO NO but I can unhook the glow plugs and it will fire up on starting fluid and run on its own. After it starts it runs great you can shut it off and it will start back up but you have to crank and crank. If you let it sit for any peroid of time it will not start. I was thinking it was a fuel priming problem but I am at a loss. I have a Snap On Soltice Pro scanner and have checked all the pressures and everthing is looking ok. Only thing that looked off was DES FRP 42 and I was only getting ACT FRP 10 while cranking when it starts it is normal. Weak pump? It has never thrown a code. I have done the bottle test and nothing was in the bottle. I have done everything I can think of. HELP!!!

By the was its completly stock with 170,000 miles

I noticed the fuel guage bounces around from time to time. I dont think that has anything to do with it.

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Well after talking to a Duramax tech everything is pointing at the cp3.

 

any tips on getting the 12mm 12 point bolts out of the back of the turbo?

 

Here is a very gooood tip for getting to the 2 lower turbo bolts. The book says remove transmission, but the way I did it was.

Removed transfer case
Removed cross member
Lowered the trans as low as possible and that will let you gain access to those bolts. Using a long extension and a good 1/2 drive impact pop the 2 bolts out.

 

Ok people... I replaced the CP3 and still have the same problem. I am loosing my mind! I can crank and crank and no smoke at all. No check engine light. I can unplug the glow plug control mod and shoot a little either and it will fire off and run perfect. It does kick out the black smoke when it is under a load. If I shut the truck off it will not fire back up. I have changed all the filters.

Is there a ICP sensor on these like the fords?

If my FICM was bad wouldnt it not run at all? I am getting 48v at the FICM.

It doesnt matter how much I prime the fuel system it will not start or smoke.

Any ideas???????

 

whats actual rail press when running?