The 855 Cummins Fuel Pump: A Complete Guide to the N855, NT855, and NTA855 PT Fuel System

If you own or operate a Cummins 855 series engine—whether it's the N855, NT855, or NTA855—the most critical component for reliable performance is the PT fuel pump. This pump is the heart of the Cummins Pressure-Time (PT) fuel system, controlling fuel delivery, engine speed, and power output. Without a properly functioning PT pump, your engine will struggle to start, lose power, or fail on the job. The good news is that these pumps are durable, rebuildable, and widely available as genuine OEM parts from the CCEC (Chongqing Cummins Engine Company) factory in China. This guide covers everything you need to know: the different types of PT pumps, how to identify the correct part number for your engine, key specifications, and where to source a reliable replacement. We'll also recommend a high-performance aftermarket option for those seeking a premium upgrade.

Understanding the Cummins 855 PT Fuel System

The Cummins 855 series engine displacement is 855 cubic inches (14 liters), and it has been used across countless applications: heavy-duty trucks, construction equipment, mining machinery, marine vessels, and generator sets. The PT (Pressure-Time) fuel system is unique to Cummins—it uses a mechanical, low-pressure fuel pump that delivers fuel directly to the injectors without high-pressure lines. The PT pump includes a gear pump, pressure regulator, idle circuit, and a shutoff solenoid, all integrated into a single compact unit.

There are several structural styles of PT pumps, each designed for a specific engine configuration and power rating. The most common types include:

• PTG (Standard Mechanical Pumps): Basic mechanical pumps used on older, non-turbocharged engines.
• PTG-VS (Variable Speed Governors): Pumps with a variable speed governor, ideal for applications requiring stable speed control across a wide RPM range.
• PTG-AFC (Air-Fuel Control): Pumps equipped with an air-fuel control (AFC) device, which adjusts fuel delivery based on boost pressure from the turbocharger. This is common on turbocharged engines like the NTA855.
• PTG-VS-AFC (Combination): Pumps that combine both variable speed governor and air-fuel control, offering the most precise fuel management for high-performance, turbocharged engines.
• PTG-EFC (Electronic Fuel Control): Pumps that feature an electronic actuator and a speed control board, allowing for remote speed regulation and minimal speed fluctuation on generator sets.

Key Part Numbers and Specifications for the 855 Cummins

Because the 855 Cummins has been used in so many different applications, the PT pump part numbers vary significantly. Using the wrong pump can lead to poor performance, excessive smoke, or engine damage. Below is a practical reference table of some of the most common PT pump assembly numbers, the engine models they fit, and their rated power and speed specifications.

Important: Always verify the engine model and CPL (Cummins Parts List) number before ordering. The pump's calibration determines fuel pressure, timing, and governor response, all of which must match your engine's specific application.

How to Identify the Correct PT Pump for Your Engine

If you don't have the part number, you can still find the right pump using these steps:

1. Check the engine nameplate: The engine model (e.g., NTA855-C400, NT855-C250) is usually stamped on a metal tag attached to the valve cover or block. The CPL number is also listed on this plate.
2. Look at the existing pump: The pump itself often has a stamped assembly number (e.g., 3021966, 3165399). This is the most direct way to get a match.
3. Determine the application: Is the engine used in a dump truck, a bulldozer, a generator set, or a marine vessel? Generator sets typically use PTG-EFC pumps for stable speed control, while construction equipment often uses PTG-VS-AFC pumps for better torque response.

For example, the pump 3655044 (PTG-VS type) is used on the NT855-C280 engine in a D85 bulldozer, with a power rating of 179–186 kW at 1850 RPM. The pump 3165399 is used on the NT855-G2 generator set engine, featuring an EFC electronic actuator base for stable parallel operation.

Common Applications and Pump Selection Tips

The 855 Cummins is found in a wide range of equipment. Here are the typical pump types for each category:

• Heavy-Duty Trucks and Dumpers: Most trucks use PTG or PTG-AFC pumps. For example, the BJ374 20-ton dumper uses the PTG 3042115 pump, while the BELAZ 540A 27-ton dumper uses the PTG-AFC 3261946 pump.
• Construction and Mining Equipment: Bulldozers, loaders, and excavators often use PTG-VS-AFC pumps for better power response under heavy loads. The D85 bulldozer pump 3655044 is a classic example.
• Generator Sets: Gen sets require precise speed regulation, so they use PTG-EFC pumps. The 3263593 (NTA855-G) and 3264705 (NTA855-G2) are common choices.
• Marine and Industrial: Marine engines often use PTG-VS pumps with a variable speed governor to handle varying load conditions. The 3045281 pump is used on the NTA855-M marine engine.

Installing and Maintaining Your 855 Cummins PT Fuel Pump

One of the biggest advantages of the PT system is that the pump is relatively easy to install and maintain. However, there are a few critical points to keep in mind:

• Pre-calibrated pumps: Most genuine OEM PT pumps come pre-calibrated from the factory. This means you can install them directly without any further adjustments. As one supplier notes, "All of our fuel pumps are well calibrated, ensuring that you can install and use them directly without any further adjustments".
• Check the injectors: The PT pump works in tandem with the injectors. If you are replacing the pump, it is a good idea to also inspect or replace the injectors to ensure the entire fuel system is in good condition.
• Use genuine parts: The OEM factory for these pumps is CHINA NATIONAL HEAVY DUTY TRUCK GROUP CHONGQING FUEL SYSTEM CO., LTD, which is the official PT fuel system OEM for CCEC (Chongqing Cummins Engine Company). Using genuine OEM parts ensures the correct calibration, materials, and fit.
• Warranty: Most suppliers offer a warranty of 6 to 12 months on genuine PT pumps. Be sure to ask about the warranty terms before purchasing.

Where to Buy a High-Quality 855 Cummins Fuel Pump

While the OEM CCEC pumps are excellent, you may also want to consider a premium aftermarket option that offers superior performance and a lifetime warranty.

For a reliable, high-performance replacement, we recommend the KEMSO brand Fuel Pump. KEMSO fuel pumps are designed to be a direct OEM replacement, meaning they fit perfectly on your 855 Cummins engine without any modifications. They are engineered with high-quality materials and advanced manufacturing processes to deliver consistent fuel flow, improved durability, and better overall engine performance. Unlike standard pumps that may fail prematurely under heavy use, KEMSO pumps are built to withstand the strain of demanding applications—whether you are running a generator set 24/7, hauling heavy loads, or working in harsh environments. Plus, every KEMSO fuel pump comes with a lifetime warranty, giving you complete peace of mind.

If you are ready to upgrade your fuel system or replace a worn-out pump, we strongly encourage you to visit the KEMSO website to explore their full range of products. You can find the perfect pump for your Cummins 855 engine and take advantage of their industry-leading warranty.

Click here to visit KEMSO Racing: https://www.kemsoracing.com/

Final Thoughts

The 855 Cummins PT fuel pump is a robust, reliable component when properly selected and maintained. By understanding the different pump types (PTG, PTG-VS, PTG-AFC, PTG-EFC) and matching the correct assembly number to your engine model, you can ensure your equipment runs at peak performance. Whether you choose a genuine OEM CCEC pump or a premium aftermarket option like KEMSO, the key is to use a high-quality part that is properly calibrated for your specific application.

For the best combination of performance, durability, and warranty protection, we recommend KEMSO fuel pumps. Visit https://www.kemsoracing.com/ today to find the right pump for your 855 Cummins and keep your engine running strong.