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Installing a Full S&S Diesel Fueling System on a 6.7 Cummins

Fuel system reliability starts LONG before an engine ever fires for the first time. As we continued assembly of a fresh 6.7L Cummins, one of the first major fuel system components to find its home was a brand-new Cummins SuperSport CP3 and a fresh set of TorqueMaster injectors from S&S Diesel Motorsport. Whether you’re doing a fresh build, replacing a failed set of injectors, or just going for a little more than stock power in your 6.7 Cummins, keep on reading!

START AT THE HEART

As the heart of the common rail fuel system, the CP3 is responsible for generating the fuel pressure required to feed the injectors, making it a critical piece of the puzzle whether the engine is destined for daily driver duty or higher-horsepower applications. One of the best parts about getting a CP3 from S&S is that they’re BRAND NEW! But if that isn’t enough to make you want one, here are some other benefits of the SuperSport CP3:

With the old pump removed from the timing case, take your fresh SuperSport CP3, and slide it onto the mounting studs on the back side of the case. Thread the nuts onto the studs and torque them to 17 ft-lb.

Next, take the pump nut and washer on the front side of the pump and torque to 77 ft-lb.

With the CP3 mounted and the high-pressure side of the fuel system beginning to take shape, let’s turn our attention to the injectors!

THE HARD PART

Few components have a greater impact on engine performance than the injectors themselves. Your injectors play a major role in everything from idle quality and throttle response to power production and fuel economy. These TorqueMaster injectors from S&S are also new bodies from Bosch, increase injector output from stock, and come with a 2-year, unlimited-mile warranty.

Let’s get to the install!

Unlike an injector replacement on an existing engine, installing injectors on a fresh build eliminates much of the disassembly normally associated with the job. With the cylinder head exposed and everything easily accessible, the focus shifts from removal procedures to proper preparation and installation. As with any common rail fuel system component, cleanliness is critical. Even the smallest contamination can create issues once fuel pressure climbs into the tens of thousands of psi.

Before installation, the injector bores and sealing surfaces were inspected to ensure they were clean and free of debris. New copper sealing washers and O-rings were used on each injector, with a light coating of clean engine oil applied to the O-rings prior to assembly. Taking a few extra moments during this stage helps prevent damaged seals and ensures each injector seats properly within the cylinder head.

One of the most important aspects of injector installation on the 6.7L Cummins is proper alignment and torque procedure. The injectors, hold-downs, and connector tubes all work together as part of the high-pressure fuel system. Following the correct torque sequence helps ensure proper sealing between components and can prevent fuel leaks or performance issues later on.

Another important consideration is the injector feed tubes. While it may be tempting to reuse existing tubes, S&S recommends replacing them whenever injectors are installed. The feed tube is intentionally made from a softer material than the injector so it can conform to the sealing surface. After multiple torque cycles, the tip of the tube can become deformed, potentially leading to sealing issues or even creating small metal burrs that could damage an injector. A leaking feed tube can also create rail pressure issues that are often difficult to diagnose, sometimes mimicking the symptoms of an undersized or failing fuel pump. Installing new feed tubes during injector installation is relatively inexpensive insurance compared to the time and expense of chasing fuel system problems after the engine is back in service.

With the injectors secured and connector tubes installed, the remainder of the valvetrain and fuel system components can be assembled. On a fresh engine build, this is also an excellent opportunity to verify valve lash settings and perform a final inspection before the valve cover is installed.

 READY FOR THE ROAD

While injectors may not be the most visible part of a Cummins build, they are undoubtedly one of the most important. Proper installation, attention to detail, and maintaining a clean work environment help ensure the engine receives the fuel delivery it needs for years of reliable service. Whether the goal is a stock daily driver or a high-horsepower performance build, starting with a properly installed CP3, injectors, and feed tubes is an investment in the long-term health and reliability of the engine.

Shout out to the team at S&S Diesel Motorsport for supporting the mag and our newest editorial build—we wouldn’t want anything else fueling our fresh Cummins engine!

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S&S Cummins SuperSport CP3  

• 6.7L Cummins-based Bosch CP3 (2007.5-2018)
• Brand-new direct from Bosch (no remans)
• Extremely durable design
• Forged steel body
• Polygon with eccentric cam
• 3 cylinders
• Plunger matched to bore for extremely tight tolerance (less leakage)
• 8.2 mm stroke x 7.5 mm bore
• 1,087 mm³/rev total displacement
• Feed and return – M12 x 1.5 female
• High-pressure outlet – M14 x 1.5 male
• Optimized for better high-speed performance up to 5,500 rpm