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-   -   LML: CP4 Bomb? (https://www.dieselplace.com/forum/63-gm-diesel-engines/365-duramax-fifth-generation-2011-2016-lml/711089-cp4-bomb.html)

marcalle 02-21-2015 04:18 PM

CP4 Bomb?
I've been reading and researching this for a few weeks now and I'm getting concerned that my truck will eventually grenade.

Leads me to a few questions:
What are the actual chances of this happening to my truck?
Anything I can do to prevent it from happening (I presume no...or replace it with a CP3)
Any warning signs that it is dying?
How hard is it to replace the CP4 with a CP3? Is it something I can handle myself (with limited knowledge), or should I take it over to Merchant Auto and see if they will do it?

Anything would be helpful. There is just so much conflicting information about when it goes, how it goes,etc. It looks like it will go at some point, but I'd like to prepare before I have a $45,000 paperweight.

D.Camilleri 02-21-2015 06:41 PM

How many miles on your truck? Any mods? Be careful what you read on the internet because sometimes the advice is tainted. Somewhere on this site there is a LML that is all stock and has over 700k on the clock with no mention of a failed cp4.

marcalle 02-21-2015 08:21 PM

Yeah I saw the 700k one. I only have emissions removed and tuned for that. I'm going to get a lift pump. I have 60k miles.

redwngr 02-21-2015 08:22 PM

There is a cp4 poll running on one of the other sites.

Last I looked, 185 had responded, and 14 had failures or 7.5%.

I suspect those with failures are a lot more likely to respond.

If it's your truck a failure is obviously not good, but it also apparent that don't fail near as often as some would have you believe.

TheBac 02-21-2015 10:16 PM

I would think if you use a lift pump to reduce strain on the pump, and decent filtration changed at reasonable intervals, then that may help. Not all that familiar with the LMLs in the first place, but it seems reasonable.

Doodle 02-21-2015 10:48 PM

There are issues with the new HPFP's but if I had to guess failure rates are probably less than 5%. To me even if it is 1% it is an issue because if they fail it is a catastrauphic failure that will cost a ton to fix. I'm not convinced this is gonna be a LB7 type issue where there is a high likelihood you'll have to replace injectors in almost every case, because there are some high mileage LML's out there with no fuel pump problems whatsoever.

From my research I think the best thing you can do is to try and get good fuel from a reputable place, use a Lubricity additive, change filters often, and don't tune it unless you run a lift pump.

No one I know has ever had an issue with the fuel system in an LML until just last week when my buddy was having issues starting his 2012. It wouldn't start on the first crank and even on the second attempt it was extended. He changed filters and it started ok, then he hauled some water to his cattle and filter life went from 100% to zero in just a few miles. Put another filter on now it won't even start. He had been using the plastic wix filter and admitted to me it had been a long time since he had changed the filter, like 30,000+ miles! My guess is he had a dirty or plugged filter and got some bad fuel and may have wrecked his pump. It only has 60K on it. He called the dealership and they said if he was using that Wix filter he may be screwed. He will find out this week what the damage is and I'll report as I am very curious.

rob1 02-21-2015 10:59 PM

At my dealer we have only had 2 fail requiring fuel system replacements and another one that wouldn't build pressure - just a bad pump no major failure. We sell and service lots of diesels so I don't think it's as common as what the Internet makes it look like.

GM4Life86 02-21-2015 11:24 PM

As i stated in my Build Thread. I am not aware that the CP4 on my truck has been replaced. I am certain it is original. And as far as i can tell he had a lift pump installed.As everyone else on here will tell you a lift pump will definitely help prevent premature failure of the CP4. That should of been the first thing i put back on the truck.

marcalle 02-22-2015 12:15 PM

I'm definitely looking at the FASS Titanium, but my question is the 150 vs 95. I dont want to damage anything by going to the 150, I dont ever plan on going over 600HP. I dont know what my current HP is, but its a mostly stock truck with emissions deleted (straight piped) and EFI Live tuning. I usually run the first or second tune (one is slightly over stock the other is towing).

Thoughts on that. I got the OK to pull the trigger from the wife, but dont know which to go for!

GM4Life86 02-22-2015 12:58 PM

Thats pretty much how my truck is setup. And I too have been wondering the 150 or 95! From what i gather. Anyone that has a bone stock truck and plans on keeping it that way has been using the 95. For those of us that have deleted and tuned it seems they are going to the 150. I haven't read or heard of the 150 doing any damage. Price wise its a small step up to the 150 so that is what i am leaning towards.

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