2897671 QSK Series High-Pressure Fuel Pump – 38-Litre And 45-Litre Engine Platform Pumping Element Assembly

The Cummins QSK engine family represents a modular approach to high-horsepower diesel engineering-sharing a common fuel system architecture across the 38-litre, 45-litre, and 60-litre displacements. While the QSK60 draws the most attention due to its sheer size, the QSK38 and QSK45 engines are equally critical in applications ranging from marine propulsion to industrial power generation. The 2897671 is the high-pressure fuel pump assembly specifically calibrated for these smaller-displacement QSK engines, delivering the same 2,200 bar rail pressure as its larger counterpart but with a reduced flow capacity matched to the engine's fuel demand. This article examines the 2897671's design, its calibration differences from the QSK60 pump, application fitment, and the practical considerations for workshops servicing these medium-bore engines.

Timing pin : The pump must be locked at TDC using the manufacturer's timing pin. Misalignment of even 1° of pump timing will cause a 4–5% power loss and increased smoke.

Drive coupling : Check the coupling for wear-excessive backlash (>0.5 mm) will cause timing drift and pump noise.

Torque specifications :

Pump mounting bolts : 80 Nm (M10, grade 10.9)

High-pressure pipe connections : 35 Nm (rail end), 28 Nm (pump end)

PCV connector : 15 Nm

Priming : Before starting, prime the fuel system using the manual priming pump or by cycling the lift pump. The pump will not self-prime-air in the pump head will cause cavitation damage within seconds.

PCV current feedback : The ECU monitors the PCV's current draw. A current draw >3.5 A at peak indicates a short circuit; a draw <2.0 A indicates an open circuit or high resistance.

Leak-off monitoring : The pump's return flow should be measured at idle. A return flow exceeding 1.0 l/min at 1,600 bar (pump running) indicates excessive internal leakage.

Rail pressure stability : During a load step test, the rail pressure should return to within ±20 bar of the target value within 200 ms-a slower response indicates PCV wear or a sticking plunger.

The 2897671 is used on the QSK38 and QSK45 engine platforms, which power a wide range of equipment:

Cross-reference: The 2897671 is the QSK38/45 equivalent of the 2897673 (QSK60). It is not interchangeable with the QSK60 pump-the reduced flow capacity would starve the larger engine of fuel, while fitting the QSK60 pump to a QSK38/45 would cause severe over-fuelling.

The 2897671's pumping elements are serviceable-they can be replaced in the field without removing the entire pump assembly. Each element consists of:

Plunger : Hardened tool steel, ground to ±0.001 mm tolerance, with a spiral-ground helix for precise fuel cutoff.

Barrel : Nitrided steel, with a matching ground bore (clearance 3–5 μm at 20°C).

Inlet valve : One-way check valve preventing fuel back-flow.

Outlet valve : Delivery valve with retraction, controlling pressure decay after injection.

The plunger and barrel are matched pairs-they are ground together and must be replaced as a set. Replacement elements are available as part number 2897672-A (left) and 2897672-B (right).

Q1: How does the 2897671 differ from the QSK60's 2897673 pump?
A: The 2897671 has a smaller plunger diameter (12.0 mm vs 14.0 mm) and a shorter stroke (15.0 mm vs 18.0 mm), delivering approximately 30% less flow at rated conditions. The pressure capability (2,200 bar) is identical, but the flow is matched to the QSK38/45's lower fuel demand.

Q2: Can I use a 2897671 on a QSK60 engine as a temporary replacement?
A: No. The 2897671 cannot supply enough fuel for the QSK60's 2,500 hp rating-it would starve the engine of fuel at full load, causing a loss of power and potentially damaging the injectors due to inadequate cooling (fuel flow helps cool the injectors).

Q3: What is the recommended service interval for the pumping elements on the 2897671?
A: In typical marine or genset applications, the pumping elements last 8,000–10,000 hours. However, this depends on fuel quality. We recommend monitoring the leak-off rate-when it exceeds 1.0 l/min at 1,600 bar, the elements should be inspected and likely replaced.

Q4: What causes the PCV on the 2897671 to fail?
A: The most common cause is fuel contamination-abrasive particles wear the PCV spool and bore, causing erratic pressure control. Also, high fuel temperatures (>70°C) can degrade the solenoid insulation. Ensure the fuel cooler is functioning and that the fuel filters are changed at the recommended interval.

Q5: Can I rebuild the PCV myself, or must it be replaced as a unit?
A: The PCV is a sealed, calibrated unit. It can be disassembled for inspection, but the spool and bore are matched pairs and cannot be replaced separately. If the PCV is worn, the entire valve assembly must be replaced-no service parts are available for the internal components.

Q6: How do I verify that the 2897671 is correctly timed to the engine?
A: Use the manufacturer's timing pin and follow the procedure in the engine service manual. After installation, check the injection timing using a timing light (if fitted) or by measuring the cylinder pressure trace. A correctly timed pump will show the injection event at the specified crank angle.