Buy wp20598 - Genuine Cummins Fuel Injector ISB/QSB 5.9L - 1 - wisentpartscenter.com

Description

The Genuine 3947550 Cummins Fuel Injector is a high-pressure common rail diesel injector designed for compatible Cummins ISB 5.9L engines. Manufactured using Bosch common rail injection technology, it delivers precisely metered fuel into the combustion chamber to support efficient combustion, smooth engine operation, and reliable power delivery. This injector family is commonly used in 2003–early 2004 Dodge Ram 2500 and 3500 trucks equipped with the 5.9L Cummins diesel engine.

Key Functions

- Delivers precisely controlled amounts of high-pressure diesel fuel into the combustion chamber.
- Atomizes fuel for efficient mixing with compressed air.
- Controls fuel injection timing and duration according to engine control module commands.
- Supports smooth idle, consistent acceleration, and engine power.
- Helps maintain proper combustion efficiency and fuel consumption.

Fitment & Specifications

- Engine: Cummins ISB 5.9L
- Engine Displacement: 5.9L (5,883 cc)
- Vehicle Applications: Dodge Ram 2500 and 3500
- Model Years: 2003–early 2004, depending on engine serial number
- Engine CPL: 8213, 8228, 8412
- Fuel System: Bosch High-Pressure Common Rail (HPCR)
- Injector Type: Electronically controlled solenoid injector
- Manufacturer: Bosch
- Quantity: 1 fuel injector

Verify fitment with us before ordering to ensure the correct part for your application.

Purpose of the Part

The Cummins 3947550 fuel injector delivers high-pressure diesel fuel directly into the engine's combustion chamber. The engine control module electronically controls when the injector opens and how long it remains open, allowing the fuel system to regulate injection timing and fuel quantity.

Proper injector operation is essential for consistent combustion, efficient fuel delivery, smooth engine performance, and reliable starting. Worn or leaking injectors can disrupt fuel atomization and cylinder operation, affecting both engine power and fuel efficiency.

Issue Symptoms / When to Replace

A worn or malfunctioning fuel injector can cause several engine performance problems, including:

- Hard starting or extended cranking.
- Rough idle, engine misfires, or uneven running.
- Excessive white or black exhaust smoke.
- Reduced engine power or poor acceleration.
- Increased fuel consumption.
- Abnormal diesel knock or combustion noise.
- Excessive injector return flow or difficulty maintaining fuel rail pressure.

These symptoms can also result from worn injector connector tubes, fuel contamination, high-pressure pump problems, or other fuel-system faults. Proper diagnostic testing should confirm the cause before replacing the injector.

Brand Information

Cummins is a major manufacturer of diesel engines and power systems used in commercial vehicles, industrial equipment, and heavy-duty applications. Bosch supplied the high-pressure common rail fuel injection technology used in early Cummins ISB 5.9L engines. Bosch-manufactured injectors are engineered to deliver the precise fuel metering and atomization required by these diesel fuel systems.

Installation Notes

Maintain strict fuel-system cleanliness during installation. Inspect the injector connector tube and sealing surfaces, replace the required sealing washers and O-rings, and follow the Cummins service procedure for injector seating and fuel connection tightening.

After installation, prime the fuel system as required, check for leaks, and verify proper engine operation. Do not reuse damaged high-pressure fuel-system components.

How to Identify an OEM Part

The Cummins fuel injector can be identified by Bosch manufacturing markings and the part number engraved or laser-marked on the injector body. Known Bosch references for this injector family include 0445120018, 0445120113, 0445120210, and 0445120255. Verify the physical markings and original application to confirm the correct OEM injector.

Why Buy 3947550 From Wisent Parts Center?

  • 1 Year
    Warranty

  • Genuine Parts

    Authentic OEM parts

  • 30-Day Returns

    Conditions apply

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Warranty & Return Information
Warranty Information

Wisent Parts offers a 1-year warranty on all parts from the date of delivery. This warranty covers orders placed directly through our website. If a part fails during this period, we’re here to help - whether it’s a replacement, repair, or refund. For full details, refer to the Warranty page.

Return Information

Wisent Parts accepts returns within 30 days of delivery. All returns are subject to a restocking fee. To qualify, parts must be unused and in their original condition. For full return instructions and restocking fee details, please refer to the Returns page.