Buy 5315421 - Genuine Stanadyne 3.3G5 Fuel Injection Pump - wisentpartscenter.com

Description

Cummins 5315421 Fuel Injection Pump - Genuine Cummins / Stanadyne DB2 Rotary Injection Pump

The Cummins 5315421 is a genuine Stanadyne DB2 rotary injection pump, sold by Cummins under their own part number for the mechanical B series engines. It is a mechanical, single plunger opposed design that meters and distributes fuel to each cylinder in firing order through a rotating distributor. Mechanically governed and driven off the engine.

Key Functions:

- Meters and distributes fuel to each cylinder in firing order
- Mechanical rotary distributor design, engine driven
- Mechanically governed with built in timing advance

Fitment & Specifications:

- Cummins mechanical B series
- Stanadyne DB2 rotary injection pump
- Mechanical, single plunger opposed design

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

Purpose of the Part

The injection pump is the heart of a mechanical diesel. It draws fuel in, builds injection pressure, and the rotating distributor sends a metered shot to each injector in the right order at the right time. The governor controls fuel delivery for the throttle position and load, and the timing advance shifts injection timing with engine speed. All the fueling, timing and governing happen inside this one pump.

Issue Symptoms / When to Replace

Hard starting, low power, excess smoke, surging or hunting idle, stalling, and fuel leaking from the pump. On the DB2 a worn advance bore in the aluminum housing is a known weak spot, it causes poor timing, smoke, low power and bad mileage.

Brand Information

These pumps are built by Stanadyne, the original manufacturer of the DB2 (originally the Roosa Master design), and sold by Cummins under their own number for the B series. The genuine pump is calibrated to the specific engine's fueling and timing spec, which is what makes it run right. A pump set up for a different application will bolt on but run wrong, so matching the genuine part to your engine is what matters here.

Installation Notes

Pump timing to the engine is critical on install, set it to spec or the engine runs poorly and smokes. Bleed the air out of the fuel system before starting, and make sure the fuel supply is clean since dirt and water are what kill these pumps. After install, set the idle and check timing.

How to Identify an OEM Part

A genuine unit has STANADYNE cast into the housing along with the Stanadyne DB2 model number and a Cummins part number label. Check the numbers match your order and compare the housing, drive shaft and fitting layout to the pump coming off. Since the DB2 was built in many calibrations, matching the exact part number to your engine matters.

Why buy from Wisent Parts
  • ⏱️
    Fast shipping
    Orders before 12PM EST ship same business day.
  • 🛡️
    180-day warranty
    All parts covered from delivery date.
  • ↩️
    Easy returns
    30-day returns.
  • ✅
    Verify fitment
    Send VIN/ESN and we’ll confirm.

Shop with confidence

Warranty & Return Information
Warranty Information

Wisent Parts offers a 180-day 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.