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Discussion Starter #1
Truck just died at the lights. Had to tow it to garage, Waiting to hear from them. It made a couple skips just before dying. 93K miles 2011 GMC Duramax. It sounds like no fuel? Ive been watching youtube videos and fuel pump replacement seems like a nightmare. Replace injectors, rails, drain fuel tank along with pump. Is this right. 2011 would be LML right? with CP5 fuel pump? If this is the case what would a job like this cost? Is there any chance it could be something else that just causes the diesel to quit?
 

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LML, yes. CP4 not 5.
Dealer prices after a CP4 grenades and fills the fuel system with metal...I've seen reports of $10-$12k.

But it's becoming so common, that now a 'kit' of all the parts needed, is offered for a significant reduced price.

Many times, you'll 1st see a 'change fuel filter' warning (as it fills with metal shavings and clogs up)
Any codes thrown?
Engine light?

'11s had TCM failure issues for a sudden no-run.
Need to see what codes are thrown though.
 

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Trans Control Module....changed with the 1st year of the LML ('11), it was flaky and would crash with no notice.

Maybe your filter head developed a leak, sucking air and a loss of fuel. What was the fuel tank level at?
 

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Discussion Starter #7 (Edited)
OK, I had my filter head lose its prime over the winter so I changed it and seemed to solve that problem. It seemed like same issue today when it died so I'm thinking fuel problem? Will the TCM cause it to quit like that? It has at least 1/2 tank. I just did full brake job yesterday.
 

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Check the primer button for firmness, to see if it's leaking.

It made a couple skips just before dying.
Usually the TCM failure has lots of messages and shifting, loss of comm codes, engine skips, etc.
 

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Discussion Starter #9
I tried pumping up the primer and it was soft so I pumped it until it was firm ran back around and tried to start, still nothing. Tried priming again and it was soft so I pumped it till it firmed up and tried again, still nothing.
Before it died I felt a couple skips as I pulled up to light then it just quit. Before that it was running good. I didn't get any messages prior. Im really bummed about the CP4 pump issues. This is the first brand new vehicle I ever bought thinking it was good for around 300K. I feel even if it isn't the pump I need to get rid of it before it ends up a real problem....which it already is, I just can't trust the truck it seems.
 

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There is the option to convert it back to the reliable CP3 pump, if that's what it turns out to be.
And there's the Exergy System saver if sticking with the CP4...has a smaller mesh screen to catch the debris when/if it fails....doesn't stop it from failing, just tries to control the damage elsewhere.

Need to find out what codes are stored.
 

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Discussion Starter #11 (Edited)
Dealer is gonna hopefully look at it tomorrow and give me the verdict. What if no codes?
What % of these pumps fail you think?
A conversion to CP3 pump still sounds like a big job?
 

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Horns is right that you are ahead of the curve in coming for advise now. You need to have a little diagnosis first, including codes. Lincoln Diesel Specialties has a reasonably priced kit that has everything you need to make it good again and more reliable if it is the CP4.

Nobody could fault you for wanting to do the conversion to the CP3 regardless of the outcome of your diagnosis but there are a lot of trucks running around out there with lots of miles on their CP4 and still going strong. The main problem with the CP4 isn't that it is total junk. It does work for most people. The problem is that when it does die it takes the whole fuel system along with it.

There are a lot more people who need a new filter head than there are people who need a new CP4. Think happy thoughts for now and see what the mechanic says.

For what it is worth, a lift pump will prevent air leaks that leave you stranded.
 

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Discussion Starter #13
Thx for the input. What exactly is a lift pump? Is it a replacement or addition?
I did just replace filter head within the last yr maybe its a bad one?
 

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Just pulled my cp4 with 150k miles on the truck. Seems like it had been done before as there where some new lines and stuff on the truck. So it probabaly has less miles than that. I bought the truck at 60k so must have failed before I purchased. Pulled reg and screen was clear as could be. Like mention Lincoln diesel has a severely discounted kit to replace the cp4 or can get the same kit with a cp3. Iirc its around 2100 for the one with cp4 and depending on cp4 2300 and up. I wouldnt have the dealer do the work or supply parts as they will screw you bad. Find a good diesel performance shop to do the work if you cant and get the parts yourself from Lincoln. The job isnt terrible just time consuming.
 
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A lift pump is a low pressure pump that mounts back near the gas tank. It has two main functions. The first is that it keeps a little pressure on the system so that any leak is a fuel leak, not an air leak. A fuel leak is not a good thing but it doesn't leave you at the side of the road waiting for a tow truck. The second thing a lift pump can do for you is to allow you to install better filters for the fuel so that what the CP sees is extra clean. You can install filters without a lift pump but then the CP has to suck harder on the fuel inlet which can lead to more air infiltration or even cavitation.

Installing a lift pump is a good thing that isn't essential but lots of us think it is worth while. It is the same sort of thing as changing out the CP before it fails. You don't have to do it but nobody is going to call you an idiot for doing it. Just don't get carried away with the fuel delivery ratings of some lift pumps. 50 GPH is all you can use on a street truck. The big pumps are just big. It's like having a 12 incher. It might give you something to brag about but otherwise it isn't of much use.
 

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Just to put it out there....

The first lift pump I ever did lasted about a week and then came back. Since I didn't consider myself an expert on the subject I sent my customer to another shop that specializes in diesel pickups. They had the tools to diagnose it properly. Their diagnosis said that the lift pump had failed again. They replaced it and the pump was warrantied. I didn't do anything wrong. The reman pump I used was defective. I just didn't have the confidence yet to continue on. Now I do.

This job takes a lot of time and patience but there are no big road blocks. There's just a lot of stuff in the way. I'd do it again without hesitation.
 

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Ill check it out, thx. Is that about the going rate for r&r fuel pump?
Let's say 2200 for the parts kit, and 2-3500 to tear down and reinstall at a good diesel shop. Probabaly books for 30 or so hours but could be done in 15 or so. All depends on if you're deleting at the same time or re installing all the egr stuff, sticking another cp4 in or swapping to cp3. The dealer it would be anywhere from 8k to 15k.
 

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Also Lincoln diesel has the best priced kit and their customer service is great. Fwiw I wouldnt stick a cp4 back in unless you live somewhere you cant delete. Their are options for cp3 swaps without tuning though also. I just checked Lincolns site it is slightly higher than I quoted
 

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I agree with these guys. If you dont have to stick with the CP4 and can do the CP3 conversion i would go that route since its proven to be a better design and more reliable than the CP4. If you have to replace the CP4, Injectors direct has a kit you can get that is very reasonably priced. I just pulled my CP4 to do a 10mm CP3 stroker. The CP4 only has 23k miles on it if your interested i can help you out with the pump and you can install the Exergy screen onto it and be on your way. I would definitely get a Fass or Air Dog lift pump to help the high pressure pump out. Personally i had a Fass and Air dog on my trucks and will run Air Dog as it was much quieter than the Fass.
 
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