4984541 Fuel Gear Pump – Cummins ISX QSX High-Pressure Transfer Solution

You run a repair shop. A truck comes in with a P0087 code, hard starting, or a driver complaining about loss of power climbing grades. You diagnose the low-pressure side. The gear pump on the side of the high-pressure fuel pump is not delivering enough volume. The truck sits. The customer waits. Every hour of downtime eats into what you can bill. The 4984541 gear pump fits Cummins ISX and QSX platforms running CM2250 and CM2350 control modules. It bolts directly to the high-pressure pump housing. This is the part you keep on the shelf for the ISX15 or QSX15 that comes in Monday morning needing to be out by Friday.

Confirmed fitment spans ISX11.9 CM2250, ISX12 CM2250, ISX12 CM2350 X102, ISX15 CM2250, ISX15 CM2350 X101, QSX11.9 CM2250 ECF, QSX12, and QSX15 CM2250 ECF. These engines appear in long-haul tractors, concrete pumps, mining haul trucks, and stationary power units. In markets where fuel quality fluctuates and maintenance intervals stretch, the gear pump is often the first component to show pressure loss, making it a high-turnover item for parts wholesalers.

Before mounting the replacement, confirm that no metallic debris from the failed unit has entered the high-pressure fuel pump inlet. The gear pump seats against the high-pressure pump housing with a new gasket, and the four mounting bolts require 34 N·m [25 ft-lb] . Index the input shaft to the drive coupling before tightening. If the original failure produced fine particles, flushing the supply line to the fuel filter housing is advisable to protect the pressure control valve and injectors downstream.

A worn gear pump may still rotate without obvious external signs while delivering insufficient flow. Symptoms include extended cranking, low rail pressure at idle, and a P0087 code that returns after filter replacement. In the common rail architecture, the gear pump must deliver enough volume to pressurize the high-pressure pump inlet; when output drops, the fuel rail cannot maintain commanded pressure under load. For repair shops, replacing this gear pump early is cheaper than absorbing the cost of a high-pressure pump replacement caused by starvation.

Q1: We order 20 units per quarter for our wholesale operation. Does the gasket come in the box, or do we need to source it separately?
A: The pump ships as the assembly only. Order gaskets in the same shipment. Mixing batches from different suppliers risks fitment variance on the mounting flange.

Q2: How many of these have your customers installed in QSX15 generator applications that run 24/7?
A: Genset duty puts the pump under constant load without road-speed cooling. In those applications, seal life depends on fuel temperature. If return fuel is hot, the pump runs hotter. Adding a fuel cooler circuit where possible extends service interval. We have distributors running these in QSX15 ECF units with good results when filtration is maintained.

Q3: We installed one three months ago, and the truck came back with the same low-pressure code. What should the technician check first?
A: Check inlet restriction before condemning the pump. A collapsed fuel line or restricted filter housing can mimic gear pump failure. If inlet restriction is within specification, verify that the drive gear engagement is correct and that the pump was not installed dry. Running the pump without fuel for even a short period during startup can score the gear faces.

Q4: What is the typical wholesale price break at 50 units, and what is the lead time for a mixed pallet of ISX and QSX applications?
A: Pricing scales with volume. Mixed-model pallets ship within standard lead time because the same gear pump covers both ISX and QSX part numbers. Consolidate your order to hit the better freight tier.

Q5: We are in a market where fuel sulfur content is higher than Euro spec. Does this affect gear pump lifespan?
A: Higher sulfur accelerates corrosion on internal surfaces when moisture is present. The bigger risk is particulate contamination. If your customers are not changing filters at half the recommended interval, the gear pump sees more abrasive particles. In those markets, recommend shorter filter intervals alongside the pump replacement.