Cummins 4307242 Supply Pump | OEM Fuel Lift Unit For QSK23 Industrial Engines

In high-displacement diesel platforms, common rail performance is often judged solely by peak injection pressure. However, the true bottleneck is frequently the low-pressure supply side. The Cummins 4307242 fuel pump assembly acts as the primary hydraulic buffer for the High-Pressure Common Rail (HPCR) architecture used in the Cummins QSK23 engine family.

Without a reliable flow of dense, bubble-free diesel delivered to the high-pressure radial pistons, the entire common rail system risks experiencing rapid pressure drops and cavitation. The 4307242 pump ensures the primary low-pressure gallery stays completely filled and pressurized. This precise control protects the downstream electronic actuators from structural stress and helps heavy equipment operations maintain a smooth, steady power output.

 

📊 Verified Engineering Specifications & Supersession Data

 

To help fleet managers and parts procurement teams ensure accurate component cross-referencing, the physical and operational parameters of the 4307242 assembly are detailed below:

Technical Attribute	Certified Specification / Operational Value
Primary Part Number	4307242
OEM Cross-References	4087997, 4903531, 2897672, 4009881, 4010566, 4076753
Factory Service Kit Reference	4307242EK80
Target Engine Class	Cummins QSK23 (CM500, CM2250 K109, CM2350 K127 Series)
Cross-Industry Application	Komatsu SAA6D170E Heavy Equipment Engines
Unit Dry Weight	Approximately 49.15 lbs (22.3 kg)
Chassis Metallurgy	High-Density Forged Iron Casting (Anti-Vibration Formed)

 

 

 

The internal layout of the 4307242 lift pump focuses on protecting fuel density before it reaches the main common rail pressurization stage:

Vapor-Lock Elimination Channeling: The internal fluid path is designed to continuously self-vent small air pockets, preventing vapor lock during high thermal return cycles.

Dual-Zone Journal Bearings: Hydrodynamic internal bushings use the diesel fuel itself for lubrication. They are hardened to resist wear from lower-lubricity modern winter fuels and ultra-low sulfur diesel (ULSD).

Volumetric Consistency Control: The internal gear profiles maintain steady fuel flow even when high engine vibrations cause rapid shifts in inlet restriction.

 

 

The 4307242 pump is primarily used in extreme industrial environments that require unyielding equipment runtime:

Ultra-Class Mining Machinery: Installed on massive earthmovers like the Komatsu D375A-5 crawler bulldozer and PC1250-7 heavy-duty hydraulic excavators.

High-Tonnage Material Hauling: Powering autonomous and manual mining trucks, wheel loaders, and blast-hole drilling rigs operating in remote areas.

Heavy Duty Oilfield & Power Generation: Providing dependable fuel transport for offshore drilling power packs and high-kilowatt standby emergency generators.

 

 

To maximize the working life of the 4307242 assembly and shield the common rail system from secondary damage, service technicians should focus on three main diagnostic areas:

Inlet Vacuum Assessment: Check suction restriction regularly. If vacuum levels exceed factory specs, the pump will cavitate, causing internal pitting and introducing fine metallic wear particles into the high-pressure system.

Water Separation Protocols: Water contamination destroys internal fluid-film lubrication. Ensure the primary water separator is drained daily to prevent internal component corrosion and premature gear scuffing.

Interface Gasket Inspection: When replacing or servicing the pump, always verify the driven gear alignment. Misaligned gear engagement can create uneven shaft loads, causing the primary lip seal to leak engine oil into the fuel path.

 

 

Q1: Why does the 4307242 pump replace so many older Cummins part numbers like 4087997 and 4903531?

A: The 4307242 is the latest upgraded design from the factory. It combines several older mid-generation parts into a single standardized unit, featuring better internal flow geometries and stronger internal seals to handle modern fuel blends.

Q2: What is the main operational symptom that tells me the 4307242 lift pump is failing, rather than the high-pressure injection pump?

A: A failing lift pump usually shows up as long engine cranking times, fuel pressure hunting at low idle, or a sudden loss of power under load. These issues happen because the low-pressure supply gallery cannot deliver enough fuel volume to feed the high-pressure common rail cylinders.

Q3: How does this component help prevent high-pressure common rail pressure codes under full machine load?

A: The 4307242 pump maintains stable fuel supply pressure to the high-pressure injection loop. This prevents cavitation pockets in the high-pressure chambers, allowing the electronic pressure regulator to accurately control system pressure without overcompensating.

Q4: Can the 4307242 assembly be safely used in marine environments with high humidity and salt exposure?

A: Yes. The exterior casing uses a special anti-corrosion coating, and the internal seals are made from high-fluorocarbon Viton. This combination prevents external rust and stops salt-air moisture from penetrating the fuel lines.

Q5: What is the risk of using non-genuine or poorly remanufactured alternatives for this specific QSK23 part number?

A: Poorly remanufactured pumps often have loose internal tolerances. This leads to internal fuel slippage as temperatures rise, causing a drop in supply pressure that can starve the high-pressure pump and lead to expensive common rail component damage.

 

 

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