CP4.2 Bypass kit

Yeah, the Ford filters are 10 microns at 98% efficiency according to Ford. GM's only filter seems to be a 4 micron, but is a depth coalescer just like the Cummins primary.

The Cummins primary filter is 3 micron inner and 6 micron outer at 98% efficiency and the secondary has a 3 micron inner and 5 micron outer at 99% efficiency.

Racor primary filter does a great job! This engine mounted filter looks nearly new after 15k. Normally without a primary filter it would be black.

Water and air was one of the main reasons why Ram added a primary filter and fuel/water separator. Its primary job is to protect the engine(secondary) filter that also captures particles and is a fuel/water separator. It differs from most other filters because it is a depth coalescer which means it collects water within its multiple layers after the particles are filtered out instead of on its surface like most filters which degrades its water removal ability as the filter's surface gets plugged up with more and more contaminants.

I would wager if GM would have added a filter like this and a lift pump in the first place, then they probably would have had less issues.

FishOnOne wrote:
There are 3 main attributes that can cause the fragile CP4 pump to fail:
1. Fuel Contamination (water, DEF, gasoline)
2. Air in the fuel line (typically happens after a filter change)
3. Manufacturing defects of the pump

The best implementation for a CP4 pump is to have really good fuel filtration for both particulates and water. A lift pump to ensure good priming of the pump after a filter change, but still requires correct filter installation and the proper priming process in which a lot of people don't follow.

On another note if anyone believes any auto manufacturer will cover a fuel system repair if there are any signs of rust, DEF and gasoline contamination are either pushing some false agenda or lives in some alternate universe. In addition there will be a time when your beloved warranty will expire and the issues I listed except for any manufacturing defects can still bite you and your wallet.

Customers of the new 2019 Ram/6.7 cummins... tighten your seatbelt because it's going to be a bumpy ride.

From my years of Fleet management my list of issues is slightly different than Fish's in regards to hp common rail diesel injections systems:

1. Water in fuel is the #1 enemy. Most OEM filters are marginally effective at extracting emulsified water. Any free water in fuel will compromise component life.
2. Debris in fuel - anything in the 5 micron size or larger will compromise component life.
3. Liquid contamination of fuel - like filling up fuel tank of a diesel truck with gasoline. This is an operator issue!
4. Air in fuel can be an issue but a liquid tight system goes a long way in preventing this problem. Most air in fuel systems are operator or maintenance related issues that can be avoided with proper practices.
5. Manufacturing defects - yes they happen but the % is low -if all the above factors are considered.

Since the Cummins has a lift pump and a primary filter, I have no doubts this mod will be available for the CP4 soon. Another mod you can do to ensure no metal particles contaminate your injectors and rail is the Exergy improved FCA/MPROP screen with a smaller micron filter on it and a screen that is less prone to collapse.

Been thinking about this for the CP4.1 in my car, but failures on BMW's seem to be far less than the trucks. It might have something to do with the fact that the CP4.1 on the 328d maxes out at 26k psi(same as the CP3) instead of 29k psi which was the limit of older CP4's with the smaller cam lobes. The upgraded CP4's have a longer cam lobe along with a few other changes allowing for 39k psi max pressure. The new Cummins is going to be well under that regulated at 29k psi.

FishOnOne wrote:

blofgren wrote:
I paid too much money to deal with too many shortcomings on my 6.0L diesel. When I was looking to upgrade I researched the Ford 6.7L and quickly decided I wasn’t going to buy one and have to spend more of my hard earned money once again dealing with shortcomings such as the ridiculous CP4 pump. As much as I was a die hard Ford man I don’t regret my ultimate decision one bit! :B

Now that the ram/6.7 cummins has the "ridiculous CP4 pump" (your description) are you a die hard Ram man?

Uh, my 2013 that will be with me until death do us part has the trusty CP3. ;)

It would have been financially irresponsible of me to have bought a CP4 equipped truck when a much better alternative was available. :B

FishOnOne wrote:

Cummins12V98 wrote:


From what I have been told CUMMINS does not give FCA a warranty. I would have assumed the same with Navistar and Ford.

Was it the same lady that told you that cummins was going to supply engines with down stream egr?

I am not sure if he said that unless you consider the EGR part of emissions. I often wonder if that poor engineer lost her job leaking the new engine would be a 6.7 at random plant tours? :B

FishOnOne wrote:

Cummins12V98 wrote:


From what I have been told CUMMINS does not give FCA a warranty. I would have assumed the same with Navistar and Ford.

Was it the same lady that told you that cummins was going to supply engines with down stream egr?

Not sure how that got started but it was ALPAR, not her.

Cummins12V98 wrote:


From what I have been told CUMMINS does not give FCA a warranty. I would have assumed the same with Navistar and Ford.

Was it the same lady that told you that cummins was going to supply engines with down stream egr?

Cummins does give FCA a warranty on every engine just like they do with all of their medium/heavy duty customers. In the light duty world, the vehicle manufacturer is the middle man for the warranty. Basically Cummins gives FCA the warranty who then gives their version of it to the end user. This is done on purpose because it forces the customer to only go to that manufacturer's dealer and FCA can put their own stipulations on the warranty.

In the heavy duty world, the warranty is between the end user and Cummins so the manufacturer is not a middle man and cannot alter the warranty given by Cummins. Also, all of the manufacturers offer Cummins engines in their trucks so you can go to any certified dealer or even a Cummins distributor for a Cummins warranty even if it is not a dealership for the truck make.

Another main reason light duty manufacturers are the middle man is because the they use their own ECM's for the engine with unique programming for their vehicle while the medium/heavy duty trucks use the ECM and programming from Cummins. Basically, you can't use Ford's Oasis or Cummins' Insight software to access and change calibrations in a Ram ECM, but if you have Cummins Insight then you can access any Cummins engine ECM regardless of make in medium/heavy duty trucks.