CP4 Question

[Userwog]

@Userwog I would be careful and make sure you get a Fass authorized dealer to install the new lift pump as the new generation 2020 2500/3500 have a different fuel assembly than the early model 2020 Ram 2500. I have a late model 2020 (08/20 mfg date) and my fuel assembly is different and required more modification to get the Fass system setup, even Fass hasn't done this yet. If you have an early model 2020 you should still have the same fuel assembly as the 2019 series. Lucky for me the guy that installed my pump is a Fass Authorized dealer and is very familiar with this system and was able to get mine going but required extensive modification. As of right now I am the first one to be done in my state and region.

Good to know for sure, and I appreciate the insight. Whereas I purchased the fass system from an authorized dealer, I did the install myself with the aid of their instructional video with no complications. Which tells me that I must have the older fuel system used in the 2019 models.

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[RamIt]

Yeah I thought the same thing. This one came in running but had high rail pressure code.

Called star to order pump and told them it was a new style. They had me check volume on transfer pump. They thought maybe transfer pump came apart and put metal in system.


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Please post what the ultimate cause of failure is because if the gen 2 pumps are failing under the same principles as the gen 1 pumps, this is important information. That will change the game in terms of preventative maintenance.

Although, I'm still a firm believer that the majority of these pump failures are coming from bad fuel regardless of design. A CP3 will still **** the bed if you throw bad diesel in the tank.

I run no additives in my truck, buy fuel once a month (unless I'm traveling) from a high volume station, and everything seems peachy. On my 15 I used to throw a bottle of 2 stroke oil in the tank every couple of fill ups just for good measure, but seems like dumping anything under than ULSD in the tank on these 5th gens is giving FCA the upper hand in warranty denials.

I'm interested though because I'm getting some noise from the engine bay on my 19, which I'm under the impression is a bad belt tensioner (which is also apparently a thing on a f**king $75k truck), so I'm dropping the truck in my service drive in the AM to have that looked at.

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[Mdavlee]

@Userwog I would be careful and make sure you get a Fass authorized dealer to install the new lift pump as the new generation 2020 2500/3500 have a different fuel assembly than the early model 2020 Ram 2500. I have a late model 2020 (08/20 mfg date) and my fuel assembly is different and required more modification to get the Fass system setup, even Fass hasn't done this yet. If you have an early model 2020 you should still have the same fuel assembly as the 2019 series. Lucky for me the guy that installed my pump is a Fass Authorized dealer and is very familiar with this system and was able to get mine going but required extensive modification. As of right now I am the first one to be done in my state and region.

I used a sump on mine and retained all the factory stuff in the tank. If my Fass dies on the road I can unplug the harness and quick connect on the injection pump and go back to driving. I thought that was the better way to go in my case since I travel all over the country.

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[Chrisn162001]

Please post what the ultimate cause of failure is because if the gen 2 pumps are failing under the same principles as the gen 1 pumps, this is important information. That will change the game in terms of preventative maintenance.

Although, I'm still a firm believer that the majority of these pump failures are coming from bad fuel regardless of design. A CP3 will still **** the bed if you throw bad diesel in the tank.

I run no additives in my truck, buy fuel once a month (unless I'm traveling) from a high volume station, and everything seems peachy. On my 15 I used to throw a bottle of 2 stroke oil in the tank every couple of fill ups just for good measure, but seems like dumping anything under than ULSD in the tank on these 5th gens is giving FCA the upper hand in warranty denials.

I'm interested though because I'm getting some noise from the engine bay on my 19, which I'm under the impression is a bad belt tensioner (which is also apparently a thing on a f**king $75k truck), so I'm dropping the truck in my service drive in the AM to have that looked at.

I’m not going to be able to tell you ultimate cause of failure other than it looks exactly like old style cp4 failures.

I don’t fully agree that it’s bad diesel or an air cavitation issue causing these pump failures.

I’ve maybe replaced 10 CP3s over last 6 years.

I’ve seen a lot of fuel contamination over last 6 years and most ran perfect after dumping the tank and putting fresh diesel most would need an injector before they needed a pump.

And if it truly is a fuel contamination issue maybe we should have kept the more resilient CP3 pump.

And yeah I’ve replaced belt tensioners on trucks with 2k miles on them LOL.


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[RamIt]

I’m not going to be able to tell you ultimate cause of failure other than it looks exactly like old style cp4 failures.

I don’t fully agree that it’s bad diesel or an air cavitation issue causing these pump failures.

I’ve maybe replaced 10 CP3s over last 6 years.

I’ve seen a lot of fuel contamination over last 6 years and most ran perfect after dumping the tank and putting fresh diesel most would need an injector before they needed a pump.

And if it truly is a fuel contamination issue maybe we should have kept the more resilient CP3 pump.

And yeah I’ve replaced belt tensioners on trucks with 2k miles on them LOL.


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Root cause of the CP4 failure is the one thing that has yet to have a hard determination factor on it.

Considering the low failure rate across the product line as a whole, I think it's just a lack of data.

I will say that the CP3 does have a reputation for being significantly more reliable, even in built stroker setups.

But considering that the CP4 issue isn't solely a Ram issue, definitely means there should be something out there that can truly define why they break.

However, to the best of my knowledge, RAM is the only brand using the CP4.2 vs the Ford/GM CP4.

And confirmed today, noise is bad belt tensioner (13k miles).

Getting new tensioner & belt tomorrow.

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[Chrisn162001]

Power strokes got the cp4.2 from 11 to present. Duramax used cp4.2 from 11-16 In the lml series engines.

The difference between a cp4.2 and a cp4 is the cp4.2 uses two valve/roller assemblies to pump fuel vs one.

The issue has been the same in all cp4s the cam roller assembly turns in the bore and no longer rolls with the cam but instead grinds the cam.

Whether that’s lack of lube or bad fuel i personally don’t know. The engineers do know exact failure. My opinion if it was lube or bad fuel we would have a tsb for no other reason but to avoid 15k warranty claim tickets.

They don’t give us techs the equipment, authority and they won’t pay us to open up the pumps so I don’t care to know the exact cause of failure. All I know is CP3 is far superior to the cp4 no matter what version it is.


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[Houston HB]

Please post what the ultimate cause of failure is because if the gen 2 pumps are failing under the same principles as the gen 1 pumps, this is important information. That will change the game in terms of preventative maintenance.

Although, I'm still a firm believer that the majority of these pump failures are coming from bad fuel regardless of design. A CP3 will still **** the bed if you throw bad diesel in the tank.

I run no additives in my truck, buy fuel once a month (unless I'm traveling) from a high volume station, and everything seems peachy. On my 15 I used to throw a bottle of 2 stroke oil in the tank every couple of fill ups just for good measure, but seems like dumping anything under than ULSD in the tank on these 5th gens is giving FCA the upper hand in warranty denials.

I'm interested though because I'm getting some noise from the engine bay on my 19, which I'm under the impression is a bad belt tensioner (which is also apparently a thing on a f**king $75k truck), so I'm dropping the truck in my service drive in the AM to have that looked at.

do you mind sharing how or what you did.

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[Gerald636]

Can you send pics of a CP3 vs CP4 I would like to know which one I have on my truck?


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[Chrisn162001]

Can you send pics of a CP3 vs CP4 I would like to know which one I have on my truck?


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What year is your truck?


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[AK Bob]

Can you send pics of a CP3 vs cp4 I would like to know which one I have on my truck


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You have a CP3 pump in your 2014.

The CP4 was introduced to RAM trucks in 2019 with the 5th Generation.


2014 RAM 3500 (Aisin) 3.73 4X4 Limited Crew Cab Long Bed DRW. Oil Bypass Filter, Fuel Filtration Kit and 50 Gallon auxiliary fuel tank.

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