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I've never had 1 where I got away with just doing a pump. At bare minimum you're doing pump, all 8 injectors, both rails and the return lines. You can usually get away with flushing lines and the rest of the system though. I learnt that the hard way on a bus, tried to get away with not doing injectors and it came back on me with long crank when hot.

GM actually sells it as a kit now, the kit includes 8 injectors, pump and both rails. The rest is ordered on its own.

We've only seen 3 pickups in the 3 years I've worked at my shop with pump failures, the other 5 or 6 were buses, and they've all been within the last 2 years. They use the same fuel source for all their vehicles and the setup is a little different as it has a small electric pump on the frame rail too, it's actually an LGH engine code.
 

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What is interesting is that I have read where Canadian blended fuel has more additives and a lower SCAR rating compared to American blended fuel, hence failures have been less common up north. Don't know if there is any truth to that or not.

One thing I can't seem to nail down is that supposedly the 2015 pickups have an "updated" CP4 but I haven't been able to determine what the update is or whether the update is even true? In addition I can't remember where I saw this but I thought I read that someone with a new 2015 has had a failure. However, most of the failures I have read about have been the 2011-2012 models. That would tend to make more sense as those theoretically should have more miles.


could be the scar rating of Canadian fuel as well as the colder weather for 9 months out of the year. are they failing due to heat as well as lubricity? as far as the updated pumps on the 15's as I have been researching the cp4 after purchasing a 2012 lml, it seems 15's are having there cp4s go out too.
 

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The R&R itself is a big job, I can't imagine converting to an older pump. I'm inclined to think that any pump failures are bad luck as long as you're keeping up with your maintence - similar to any other failure.

I've got one in my stall right now at work with the metal filings from the pump (only second one we've seen) and I'll keep my eyes peeled for any possible causes but I think the general will deny the warrenty claim if I disasemble the old pump.




Rob, have you seen anymore pump failures since your post in February?
 

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No. it must be removed dis-assemble and visually inspected.


I was curious how many of these pumps have you seen or heard of going bad and taking out the fuel system. Is it going to happen at some point in time in your professional opinion? if so would it not be a smart decision to pay the 3k to convert to a cp3 instead of waiting for the pump to take system out and cost 10k out of warranty?
 

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Hello Everyone. I've been a member DL since 06 when I purchased my 06 crewcab LWB, put 326k on it with NO problems.
Always viewing the forums, just don't post much.

Purchased 2016 crew with LWB in May, at 13k miles, sitting at a traffic light, dash indicator lights up saying change fuel filter, light turns green, step on accel truck goes into limp mode, then shuts off as I'm rolling thru the intersection.

Just got it out of the shop from the dealer after 5 WEEKS.

Tech said that the problem is the rollers in the pump are like chrome plated and the chrome plating is disintegrating, leaving metal flakes in the fuel system, therefore trashing the pump as it pushes the metal back into the fuel tank and back to the pump again.

So it's not the fuel we're buying. Additives aren't helping, the problems are everywhere but seem to be happening more in Arkansas and Texas according to dealer, the reason for the long turn around in the shop is due to parts being on back order due to demand.

I can NOT say anything bad about my dealer, they were GREAT thru the process, provided a loaner truck during the down time and reimbursed for monthly payment.
 

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Hello Everyone. I've been a member DL since 06 when I purchased my 06 crewcab LWB, put 326k on it with NO problems.
Always viewing the forums, just don't post much.

Purchased 2016 crew with LWB in May, at 13k miles, sitting at a traffic light, dash indicator lights up saying change fuel filter, light turns green, step on accel truck goes into limp mode, then shuts off as I'm rolling thru the intersection.

Just got it out of the shop from the dealer after 5 WEEKS.

Tech said that the problem is the rollers in the pump are like chrome plated and the chrome plating is disintegrating, leaving metal flakes in the fuel system, therefore trashing the pump as it pushes the metal back into the fuel tank and back to the pump again.

So it's not the fuel we're buying. Additives aren't helping, the problems are everywhere but seem to be happening more in Arkansas and Texas according to dealer, the reason for the long turn around in the shop is due to parts being on back order due to demand.

I can NOT say anything bad about my dealer, they were GREAT thru the process, provided a loaner truck during the down time and reimbursed for monthly payment.
did the tech say if it was just the new (upgraded) pumps on the 15s and 16s that have chrome on them or all cp4 pumps? if it is all of them that is crazy. so I am guessing they put the a cp4 back in your truck.
 

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I thought the pumps had ceramic balls and that's what explodes -sending shards into the inj/lines/tank?
 

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I thought the pumps had ceramic balls and that's what explodes -sending shards into the inj/lines/tank?


From what I have read that is correct it has ceramic balls that wear our and when they go it causes other internals to fail and scrape the pump causing metal shavings to go through the system. I have also seen mechanics say the piston skirt or material breaks down. some say the rollers break down. either way if this is bound to happen to the cp4 at some point that is going to get expensive if it is out of warranty. Some say they are not worried about it and it is only 5 or 10 percent of owners but I would think the majority of them would then fail at some point over the vehicles useful life span.
 

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My 2011 has been having issues for a year and a half... And it finally died. Had a shop check the FPR for metal, and there was some... Wouldn't start afterwards.

11 days out of warranty, and 300km out of extended warranty.

The up shot, is that GM does warranty CP4 failures, even with a tuned truck.... But they don't back date, lol.


A lift pump with filters will help it last longer... Which, depending on the age of your vehicle, can be worse.

CP3 conversion is the way to go. Stock LBZ pumps are fairly affordable, compared to modded pumps.
 

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Bought my Duramax a year age not knowing of the CP4 failures. Since hearing about the problem I have read that the best way to help the pump is to buy from a reputable station, change your fuel filter at no less than 20%, put fuel additive in every fill up to increase lubricity. I chose OPTI Lube. Last you can add a lift pump or do the CP3 conversion. Any thoughts?
 

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I have a 2011 duramax 3500hd and the bomb went off on me change it before you have to replace the whole fuel injectors fuel lines to drop tank to clean cost me 7000.00
 

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Get the better fuel pressure regulator and screen. It will catch all the metal before it leaves the regulator on the hpfp. Just have to change the pump then. The factory screen isn’t fine enough plus they are known to let go and even larger particles get by.


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Can you tell me more about the said screen. Part numbers, etc. Thanks!!
 

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Can you tell me more about the said screen. Part numbers, etc. Thanks!!


It’s the Exergy System Saver. Some report you have to take a lot off of the motor to install. I didnt and had never done it before. It took less than an hour for me to change it. You will need a 6” T25 Tory bit to reach it. It’s the only bit that will reach the two screws on the base. You have to take the 4 bolts out of the air conditioner compressor base and set it aside to reach down to it. Be sure to blow the FRP off and around it, before you take it loose. You do not want any debris to get into the fuel system. Here’s a link to it.
https://www.wcfab.com/i-31420523-exergy-performance-system-saver-improved-stock-inlet-metering-valve-fca-mprop.html


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Without trying to read through 9 pages of CP4 talk, has anyone joined the lawsuit? I have contacted a firm out of Texas and have the contract to join but I can find now real information on what direction this has gone, what GM is doing if anything and on top of that the firms fees are contingency but 40% of recovery. Some say that is about normal but it seems high to me but then I am cheap.
 

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I have a 2014 LML totally stock, 56k, 5 months out of warranty and my CP-4 just failed. GM will only cover 45%. Total bull****. My 05 is still driving around no problems. My buddy's 2015 with 77k just failed in the same week. I'm a die hard GM guy for 30 years but f*^k them for not making it right. I drive like a grandma and take meticulous care. That CP-4 is a weak link time bomb that should be recalled.
 

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I know it’s an expensive failure, and very upsetting if you’re unlucky enough to have it happen to you, but I can assure you it’s not as common as you would think. You need to keep in mind, the posts on forums like this one are only from (rightly) upset owners. I’m sure that the failure percentage is actually lower than the internet would like you to believe.

On another note, I personally hope there is no special policy or campaign regarding the injection pump, if there is I’ll not be able to afford to feed my family anymore, the labor time was cut by more than in half for the injection pump replacement, and the procedure we have to follow if the pump fails with metal debris in the system, we get just over 12 hours to do a repair that to do correctly can take nearly 25 hours.
 
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