Community Forums

redhooker · 01-30-2020, 06:05 PM

To the OP, yes I agree you are at the time to be considering a fuel pump. The CP4 pump is found on the LML, Which was 2011-2016. Yes it’s true when it goes it generally takes all 8 injectors with it and requires about $9000 to repair, give or take.

Your options are:

1. Do nothing and wait. Some CP4s last over 200k. Some don’t last to 100k-but almost all of the early failures are in tuned trucks.

2. Replace the CP4 now. You can get this done for between $1900-$2200 depending on your local shops. A little pricey but seems cheap compared to the alternative. We have owned I believe every version of the Dmax and even the CP3s generally don’t make it much further than 200k. So your pump is definitely past its half life IMO. Also if you get this done at the dealer you will get a 30k mile warranty on the pump. Not a lot but enough warranty to ensure you don’t get a “Friday” pump. That warranty would cover downstream damage as well.

3. CP3 conversion. This is the ideal solution, and Exergy makes a great kit. This will cost almost $5000 though so I also think option 2 is a good compromise.

Adding a lift pump is a fantastic upgrade. Although I used to like the Fass the most Fleece performance has a newer design that works much better. About $800 for that one.

Good luck!

carl2591 · 02-07-2020, 05:50 AM

SO it seem to me if looking at a duramax to avoid the 2011-2016 models due to a pump that may or may not fail at a steep cost if it does. Or buy one and plan to spend 3K on a pump upgrade right off the bat..

have to say the 2015-16 6.7 cummins are sounding better or maybe ford 6.7 in the 2015-16 range ?? what a boy to do???

wawazat · 02-07-2020, 07:02 AM

There is currently a class action lawsuit against GM for the CP4 in 2011 - 2016 models.

Kraken · 02-07-2020, 10:31 PM

Quote:

Originally Posted by wawazat

There is currently a class action lawsuit against GM for the CP4 in 2011 - 2016 models.

If you have any documents on this I'd love to have it, since I have a 2016. I got the Fass, but haven't installed it yet. I really love the truck, got a good deal on it, so I'm not really fretting the cost of the Fass. It just makes it much better; the way it should be really. While I'm at it I'm going to do a sump as well. Then I'm done throwing money at it( I hope).

redhooker · 02-09-2020, 08:07 AM

Quote:

Originally Posted by carl2591

SO it seem to me if looking at a duramax to avoid the 2011-2016 models due to a pump that may or may not fail at a steep cost if it does. Or buy one and plan to spend 3K on a pump upgrade right off the bat..

have to say the 2015-16 6.7 cummins are sounding better or maybe ford 6.7 in the 2015-16 range ?? what a boy to do???

Actually the LML is a fantastic setup. A $2k fuel pump every 150k is not a big issue to me. The premature failures are rare and when occurring are overwhelmingly tuned or unmaintained trucks. With the LML you get outstanding frame and suspension upgrades, and despite being lower than the L5P the power will not leave you underwhelmed.

Every truck and generation has its issues. The CP4 is really the only one on the LML worth mentioning. The L5P has Denso fuel pump and injectors, but now you have to pull the head again to replace one injector-which Denso HAS been having numerous issues with. Not really talked about much as almost every L5P is still under warranty.

There is a solid (but different) argument to own just about every Duramax made, still a significant accomplishment for an automaker.

carl2591 · 02-09-2020, 03:18 PM

how do "they" get fuel out of the tank on the gas trucks?? Externally mounted pump or like most gas trucks the pump is in the tank. If the GMC's are like the older ford they use the same fuel tank for gas and diesel. If that is so then can you not use the internal fuel pump to move fuel to the CP4 pump?? just spitballing here.

A Don · 02-24-2020, 02:23 PM

I really appreciate all of the replies. I have been away from my PC due to a knee replacement that kept me at home.
From the suggestions made, I think I just may replace the cp4 and add a lift pump. I failed to mention I am completely deleted and run on the first "Tune". I really like the fuel mileage bump and performance.
I plan to do the replacement and upgrade as soon as I can accumulate enough cash and keep the wifey out of the decision making. She ain't too happy about the expense of the delete.

Don

WyomingTA · 03-07-2020, 04:58 PM

i have been seeing the adds for the law suit--i have a 2015 D-Max but only 31000 miles and i service it every 4000 miles with Mobil Delvac 15-40 and a qt of Lucas every time---Hoping for the BEST

captrcurtis · 04-29-2020, 02:40 AM

Just to clarify an earlier message if you have a GM dealer do any repair but specifically a pump repair the parts are warranted for 2 years unlimited mileage unless, it's repaired under warranty in which case it'll be warranted until the end of the factory warranty or 12 months or 12,000 miles whichever is greater.
The biggist issue really is lack maintenance and ultra low sulfer. Replace your fuel filer every 24,000 miles or less, change oil and filter every 5,000 miles, use only high quality oil filters and use a high quality fuel additive every 3-4 of fuel.. If the product you use states its good for gas or diesel engines quit using it. One of the best products out there can be purchased from Napa auto parts stores and is called Liquid Molly.
While there are a lot of people who complain about this issue they are a small minority yes the affected years are 2011-2016 but there have been a lot more of those vehicles that have not had the issue than that did

Kraken · 05-01-2020, 10:19 AM

I thought I would give you guys an update. I installed the Fass system and while I was at it I also did a sump. The Fass was not hard to install, you just have to make sure you hook up the hoses correctly. I can hardly hear the Fass running outside the truck unless I put my ear down there.There is only one bed bolt that holds the whole Fass system on, but it's a big one and it's nice and solid on there. The sump helps in several ways. In and of itself it provides a bit of pressure to the Fass just from the weight of the fuel since its attached to the bottom. It also helps the Fass cause it feeds it from a half inch line and not that metal straw from the factory(less resistance). The other thing it does is it doesn't allow a buildup of water in the tank. It's taking it right from the bottom and sends it directly to the Fass. Microbes live at the water/diesel interface, so a sump removes all the water, unlike the factory draw straw that has to leave a small space to so it can suck up the fuel. For lubricity I use Optilube XPD. I feel confident that my CP4 should be ok with this setup. I only have 5000 miles on my 2016.