Installing an S&S CP3 Conversion Kit on a 2019–2022 Ram 6.7L Cummins

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Installing an S&S CP3 Conversion Kit on a 2019-’20 Ram 3500

Unless you live under a rock, you’ve seen the problems with the Bosch CP4 over a few different modern diesel platforms recently. In very few cases, you can catch the problem before it causes major damage, but 8 out of 10 times you’re seeing catastrophic failures where the pump shreds itself up and sends the fuel and aluminum mixture all the way through to the injectors. How does one prevent this? Well, we’re here with The Diesel Shop in Locust Grove, Oklahoma, today to show you how to keep your factory CP4-equipped Ram on the road BEFORE it costs you big time.

S&S Diesel has once again blessed the diesel industry with an awesome product to save these cursed trucks that we’re going to walk you through today. This conversion will fix your ticking time bomb of an injection pump, further keeping the cost of the fix MUCH lower than replacing a whole engine. Now let’s get to the install with the guys from The Diesel Shop!

CP4 to CP3: Installing the S&S Diesel Motorsport CP3 Swap Kit on a 2019 Ram 6.7L Cummins

The 2019 Ram 2500 and 3500 brought the updated 6.7L Cummins platform into a new era with a revised emissions strategy, refined drivability, and a fuel system that pushed high-pressure common rail performance further than ever. It also brought one of the most discussed parts of the package: the factory Bosch CP4.2 high-pressure pump. While the CP4 can support stock output and moderate tuning, many owners who tow heavy, run performance calibrations, or simply want long-term peace of mind look to the proven Bosch CP3 design.

S&S Diesel Motorsport offers a complete CP3 conversion system designed specifically for 2019 and newer Ram applications. It’s built to fit cleanly, align correctly, and integrate with the factory fuel system architecture without turning the engine bay into a custom fabrication project. What follows is a practical, tech-based walkthrough of what the swap involves, why it matters, and the details that separate a smooth install from a headache.

1) Gain Access

On a 2019 Ram, you will spend the first portion of the job creating space. Remove the intake horn and any engine bay components that block direct access to the pump and high-pressure lines.

2) Identify and Disconnect Electrical Connections

Disconnect the factory pump connector and any related harness retainers. Be gentle with tabs and keep connectors clean. A surprising number of post-install issues trace back to a connector not fully seated.

3) Remove High-Pressure Lines

The high-pressure outlet line from pump to rail must come off. Use a line wrench and do not round fittings. Once removed, cap the rail and pump ports. Even if you plan to replace the line, keep everything sealed during the work.

This is also the point where you inspect line routing and decide how you will install the S&S-supplied line or adapter. The conversion relies on correct routing and strain-free alignment.

4) Remove the Factory CP4 Pump

Remove mounting hardware and pull the CP4 free from its mounting location. Expect some fuel spillage. Keep the area clean, and do not allow debris to fall into the timing cover area.

While the pump is out, inspect the mounting surface and clean it thoroughly. Any debris or gasket material left behind can compromise alignment or sealing.

5) Install the S&S Mounting Solution and CP3

This is where the kit earns its money. The CP3 must sit at the correct clocking and alignment for the drive interface and the line connections.

Install the bracket or adapter components per the kit instructions, then seat the CP3. Start all hardware by hand before tightening. This prevents cross-threading and helps ensure the pump sits flat.

Do not force anything. If the pump does not naturally align, stop and verify bracket placement, dowel alignment, and any spacers or shims included with the kit.

6) Connect the High-Pressure Outlet

Route the high-pressure line so it clears moving components and does not rub on sharp edges. High-pressure lines must not be under tension. Tighten fittings to the correct specification from S&S documentation. Overtightening can damage sealing surfaces. Undertightening can create a dangerous leak.

7) Reassemble Intake Components and Double-Check Everything

Before you reinstall every duct and shield, do a full pass inspection to make sure that:

• All electrical connectors are locked.
• High-pressure fittings are tight and properly routed.
• No tools or rags are left in the valley.
• Harness clips are secured away from heat and sharp edges.

8) Prime the Fuel System

Use the truck’s lift pump priming procedure, if equipped, or cycle the key multiple times to command pump operation. The goal is to purge air from the low-pressure side before you attempt extended cranking.

Do not crank endlessly. Cranking with air in the system is hard on the starter and can create misleading symptoms that look like an electrical problem.

9) Start-Up and Leak Check

Once it fires, let it idle. Do not rev it immediately. Watch for:

• Fuel leaks at low-pressure connections
• Any wetness at high-pressure fittings
• Abnormal idle surge, which can indicate air or control mismatch

A CP3 conversion on a 2019 Ram is one of those upgrades that lives at the intersection of performance and longevity. It is not just about chasing horsepower. It is about confidence when you are towing heavy, traveling far from home, or building a truck that needs to survive long duty cycles without the fuel system being the weak link.

The S&S CP3 swap kit is designed to bring that proven pump architecture back to the late-model Cummins platform with clean installation and correct integration. Follow the instructions closely, stay obsessive about cleanliness, and treat every high-pressure connection like it matters, because it does.