Cummins QSX Parts – Injector Section

The Cummins QSX engine represents one of the most durable and high-performance powerplants in the heavy-duty industrial and off-highway engine segment. Built on the same core architecture as the Cummins ISX, the QSX is designed for applications that demand continuous, high-torque power — from construction machinery to mining equipment and large generators. Central to the QSX’s performance is its fuel injection system, which ensures consistent combustion, optimal power output, and fuel efficiency across all operating conditions.

This section of the catalog focuses on rebuilt Cummins QSX injectors and repair kits, engineered for maximum reliability and precision. All components are available through Diesel Pro Power, trusted globally by over 40,000 satisfied customers for Cummins engine parts and expert support.

Overview of the Cummins QSX Fuel Injection System

The Cummins QSX engine utilizes a high-pressure common rail fuel injection system, driven by advanced ECM (Electronic Control Module) control. This system allows precise metering of fuel at high pressures, ensuring efficient combustion, lower emissions, and excellent throttle response even under extreme loads.

The QSX’s injectors are electronically actuated and designed to withstand the harshest environments — from dusty construction zones to remote mining sites. Each engine typically uses six injectors, one per cylinder, working in perfect synchronization with the ECM and camshaft timing.

Key design elements of the QSX injection system include:

• Dual overhead camshaft (DOHC) design for precise fuel and valve timing

• Electronically controlled injection events for improved fuel atomization

• High-pressure fuel rails for consistent delivery to all cylinders

• Advanced nozzle tips that ensure fine spray patterns and cleaner combustion

When any injector becomes worn, it can affect the balance of the entire system, leading to rough idling, poor acceleration, increased emissions, or reduced fuel economy. That’s why Diesel Pro Power’s rebuilt injectors are engineered to restore OEM-level precision and reliability.

Rebuilt Cummins QSX Injectors

Each rebuilt injector supplied by Diesel Pro Power undergoes a comprehensive remanufacturing process to ensure long-lasting performance equal to or exceeding factory standards. These injectors are not simple reconditioned units — they are professionally rebuilt, calibrated, and tested to perform as new.

Cummins Injector for ISX and QSX Engines – Rebuilt (Option 1)

Application: Cummins QSX and ISX Dual Cam Engines
Quantity: 6 per engine
Type: Rebuilt OEM injector
Condition: Certified and performance-tested
Availability: In Stock

This top-tier rebuilt injector provides consistent high-pressure fuel delivery, essential for maintaining power and torque in heavy-duty QSX engines. Diesel Pro Power’s technicians rebuild each unit using advanced cleaning and machining processes, replacing critical wear components such as:

• Plunger and barrel assemblies

• Check valves and seals

• Nozzle needles and tips

• Electrical solenoids (where applicable)

Each injector is then tested under load conditions that replicate real engine performance. Spray pattern, injection volume, and leak integrity are verified using Cummins-approved equipment.

Benefits of choosing this injector:

• Restores factory-level performance and fuel efficiency

• Eliminates common issues like hard starts, smoke, and uneven idle

• Built to resist internal corrosion and carbon scoring

• Guaranteed leak-free under high operating pressures

Diesel Pro Power packages every injector individually to prevent contamination during shipping and includes fitting guidance for accurate installation.

Cummins Injector for ISX and QSX Engines – Rebuilt (Option 2)

This version offers the same build quality and reliability, optimized for different CPL (Control Parts List) calibrations commonly used in later-generation QSX engines. Because Cummins produced multiple configurations for different applications, ensuring the right injector per CPL number is essential for proper ECM function and fuel timing.

Each Option 2 injector is thoroughly flow-tested to ensure consistent fuel output across all six cylinders, ensuring balance and smooth operation.

Key features include:

• Electronic control calibration matched to Cummins factory standards

• Reinforced nozzle design to withstand high combustion temperatures

• Updated O-ring materials for modern ultra-low-sulfur diesel compatibility

• Quality assurance inspection before shipping

Technical Highlights:

• Pressure rating: 29,000–32,000 PSI

• Fuel type: Diesel No. 2 / ULSD

• Typical installation torque: 44–50 ft-lbs

By maintaining proper spray pattern integrity, this injector helps reduce particulate emissions and improve turbocharger response — critical for off-highway engines working under load for extended hours.

Cummins Injector for ISX and QSX Engines – Rebuilt (Option 3)

This variation is built to support older QSX configurations as well as industrial power units and generator sets. It provides the same premium rebuild quality while offering cost-effective performance restoration.

Each unit is completely disassembled and rebuilt using new wear components and gaskets. Injector bodies are precision honed to ensure perfect sealing, and nozzle flow is balanced to within OEM tolerances.

Performance benefits:

• Improves combustion efficiency and fuel atomization

• Restores lost horsepower and torque output

• Reduces exhaust smoke and unburned fuel

• Lowers long-term fuel costs by improving burn efficiency

These injectors are a direct fit replacement — no modifications or tuning required. Simply verify your CPL number, install with new seals, and prime the system to restore performance.

Cummins ISX and QSX Injector Repair Kit

Diesel Pro Power also offers a comprehensive Injector Repair Kit for Cummins ISX and QSX engines, ideal for customers maintaining fleets or performing in-house service work.

Included Components:

• High-temperature O-rings

• Copper sealing washers

• Nozzle gaskets

• Return line seals

• Retaining clips and spacers

This kit allows technicians to reseal and service injectors that show minor leaks or degraded seals without performing a full rebuild. It’s compatible with most injector variants across ISX and QSX engines and helps extend service life between replacements.

Advantages:

• Reduces maintenance costs

• Prevents fuel dilution in engine oil

• Improves fuel pressure stability

• Ideal for proactive maintenance programs

Understanding the Role of CPL Numbers

Cummins uses CPL (Control Parts List) numbers to define unique configurations for each engine. This ensures precise compatibility among the engine’s components — including injectors, pistons, camshafts, and ECM tuning.

Matching the correct injector to the engine’s CPL number ensures:

• Accurate fuel delivery rates

• Proper injection timing

• Consistent combustion across all cylinders

• Compliance with emissions standards

Diesel Pro Power’s catalog and support team help customers identify the correct CPL and corresponding injector model to avoid costly mismatches.

Signs of Injector Wear or Failure in QSX Engines

Even the most robust injectors eventually wear due to constant exposure to heat, pressure, and fuel impurities. Early detection of injector problems can prevent extensive engine damage.

Common warning signs include:

• Hard starting or long crank times

• Rough idle or fluctuating RPM

• Excessive black or white exhaust smoke

• Increased fuel consumption

• Uneven cylinder temperatures

• Knock or rattle noises under load

If you experience any of these issues, replacing or rebuilding the injectors is often the most effective solution.

Diesel Pro Power’s Injector Rebuild Process

Every injector sold through Diesel Pro Power follows a strict quality control protocol:

1. Complete Disassembly: Each injector is fully stripped to its individual components.

2. Ultrasonic Cleaning: Removes carbon buildup and varnish from internal passages.

3. Component Replacement: Worn internal parts are replaced with new OEM-quality equivalents.

4. Precision Machining: Injector seats and plungers are honed to restore correct tolerances.

5. Assembly and Calibration: Injectors are reassembled in clean-room conditions and tested for pressure, flow rate, and spray pattern.

6. Quality Assurance: Each unit is certified for leak-free operation and fuel metering accuracy before packaging.

This level of detail ensures every injector delivers factory-grade performance and reliability right out of the box.

Installation and Maintenance Tips

Proper installation is crucial for maintaining injector performance and preventing premature failure.

Installation Guidelines:

1. Clean injector bore and fuel passages thoroughly before installation.

2. Replace copper washers and O-rings with those provided in the kit.

3. Use anti-seize lubricant on hold-down bolts if recommended.

4. Torque all bolts according to Cummins specifications.

5. Prime the fuel system to remove air pockets.

6. Verify injector calibration with Cummins Insite or equivalent diagnostic software.

Maintenance Recommendations:

• Replace fuel filters at recommended intervals.

• Use high-quality diesel to prevent clogging and corrosion.

• Periodically inspect fuel return lines for leaks.

• Follow Cummins’ maintenance schedule for injector servicing.

These steps help maximize injector lifespan and maintain consistent engine output.

Diesel Pro Power Advantage

When you order Cummins QSX injectors or repair kits from Diesel Pro Power, you gain access to:

• Global delivery with fast shipping and real-time tracking

• Over 40,000 satisfied customers in marine, industrial, and trucking sectors

• Dedicated Cummins-trained support staff for fitment and technical questions

• In-stock parts for minimal downtime

• Rigorous quality testing on every rebuilt component

• Secure online ordering and transparent core return process

Diesel Pro Power has built a reputation as the go-to supplier for hard-to-find Cummins parts, ensuring that customers worldwide keep their engines operating at peak efficiency.

Applications of the Cummins QSX Engine

The Cummins QSX series powers some of the toughest equipment on Earth. Its adaptability and reliability make it a favorite for:

• Mining Equipment: Excavators, haul trucks, and drills

• Construction Machinery: Dozers, graders, and cranes

• Oil & Gas: Pump drives and well servicing rigs

• Industrial Power Units: Compressors and hydraulic systems

• Stationary Power Generation: Standby and prime power gensets

In all these applications, dependable fuel delivery is essential. A properly functioning injector ensures consistent combustion, optimal torque, and extended engine life — even under 24/7 duty cycles.

Fuel Efficiency and Environmental Performance

The QSX engine’s fuel injection system plays a critical role in emissions reduction and fuel economy. Rebuilt injectors from Diesel Pro Power help maintain these standards by:

• Ensuring precise fuel metering

• Reducing unburned hydrocarbons

• Improving combustion efficiency

• Lowering soot and particulate output

With properly calibrated injectors, operators can experience smoother performance, faster throttle response, and measurable fuel savings over time.

Troubleshooting Tips for QSX Fuel Systems

If injector-related issues arise, here are key troubleshooting steps:

• Check for fuel pressure at the rail — low pressure could indicate a supply issue, not injector failure.

• Inspect injector wiring harness connections for corrosion or loose terminals.

• Perform a cylinder cutout test to identify faulty injectors.

• Examine returned fuel flow for excessive leakage, which may indicate worn internals.

• Use Cummins diagnostic tools to check for injector-related fault codes.

Diesel Pro Power’s technical team can assist customers with identifying symptoms and selecting appropriate replacement parts.

Long-Term Value of Rebuilt Injectors

Choosing rebuilt injectors from Diesel Pro Power provides significant value compared to buying new OEM units. You receive:

• Equivalent performance at a fraction of the cost

• Environmentally responsible remanufacturing

• Fully inspected and tested units with guaranteed reliability

• Fast availability for time-critical repairs

Because Diesel Pro Power uses precision testing and quality assurance at every stage, each injector delivers the same dependability as new parts, backed by customer trust earned over decades.