Black Beauty Build Thread

Can your post a video of this extended crank? I'm very curious, as I know someone with a similar issue, fewer modifications however.
 
Dads 05 had the same issue but exaggerated, it was the rail pressure regulator on the rear of the fuel rail. It's been a long time so I'm not sure if that's the correct name or not.
 
Maybe the PRV on the front of the rail? I'm thinking it could be the culprit but not sure and they are pricey.


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Ok well good news. Changed the oil, disconnected battery's while doing so. While changing the oil I noticed some chaffed bare wires by the compressor that go to a line sensor. Repaired those and hooked battery's back up. Cleared the code and loaded a new tune.

No codes so far and it's running good. Still takes longer to start which I can't figure out yet. Got about 7-8 psi fuel pressure at idle and it drops to about 3psi at WOT on this new very conservative tune. I'm thinking once I get it tuned better I'm going to need a better lift pump. Maintains rail pressure now also but tune is pulled way back.

Also ordered a cascade valve just to see if that helps.


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What did these wires go to exactly? Sounds like you're referring to the pigtail for the AC compressor or the low pressure switch wires.

Thanks for posting the video. I'm not much help on that issue, just curious.
 
Red Sleeper said:
What did these wires go to exactly? Sounds like you're referring to the pigtail for the AC compressor or the low pressure switch wires.

Thanks for posting the video. I'm not much help on that issue, just curious.
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Yes the wires went to either the low or high pressure switch. Not sure which on is next to the compressor.

Yeah the hard starting it what stumping me. All else seems normal. Drove it to work this morning and it was fine besides just needing to refine the tune a lot.


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This hard start reminds me of a VP truck that leaks all the fuel back. I 'think' I can smell raw diesel around the engine bay when I shut the truck off and get out. Can't see any yet. Gonna clean it up real good and keep looking.

Also seems as now I have a coolant leak somewhere. Ahhh, sending oil off for testing so hopefully it's not s HG. Can't see coolant leak anywhere either lol


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Well no external leaks of diesel. I guess I'm gonna pop all the lines off and go through the injector and connector tube sequence again.


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Did you check the return line banjo bolt located on the back side of the cylinder head?


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Red Sleeper said:
Did you check the return line banjo bolt located on the back side of the cylinder head?


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Click to expand...



No I have not. I guess I can check that before I pop the lines/injectors.


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Line on back of head is not leaking. Found coolant leak. It's the little hose under the exhaust runners 5/6. Gonna replace that. Also I disconnected cam sensor and it starts exactly the same so I ordered a new cam sensor to rule that out.


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I have that hose if you want. Just removed that exact hose on my 05 to install a coolant bypass. I'm in Houston.
 
Red Sleeper said:
I have that hose if you want. Just removed that exact hose on my 05 to install a coolant bypass. I'm in Houston.
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Thanks for the offer. I'm in Victoria. How much you want for it?


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Those little hoses are notorious for leaking , Chrysler remade them with new clamps just for that problem.
 
So on a very mild tune I'm pulling my lift pump pressure down to about 3 psi. What are people doing about this? What is safe pressure for a CP3?


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Yes, this is normal on the CR trucks. My cousin has a 06 CR G56 and can pull his fuel pressure down to 0 psi on stock tune, WOT, 5th gear with a load. Yet, rail pressure does not suffer.

My 05 CR with a 48re would drop down around 3 with a 100hp tune, 3rd gear, WOT, trailer loaded. No drop in rail pressure.

So yes, factory in tank lift pumps on these trucks can drop down low on supply pressure, yet the CP3 still functions properly. Just remember, a duramax engine uses CP3 as well with no lift pump from the factory. They rely on the built in lift pump inside the CP3 to supply adequate fuel pressure.

At the end of the day, a lift pump upgrade is always good insurance.
 
Just popped a P0191 code. It almost seems it's getting harder to start. Been monitoring oil level and it's the same. Thinking either rail sensor or rail relief valve. Does anyone have a good spare relief valve or sensor I can swap in to test?


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Well I found a $40 rail sensor and a $115 rail relief valve on ebay and both claim to be genuine NEW bosch oem product so I'm gonna give it a shot on both since they're soo much cheaper than ordering through cummins. Well see if it's too good to be true.
 
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