Johnson Pump 28512 Marine Pump Cartridge for 1000–1250 GPH 12V Black — Cartridge Replacement, Universal-Fit

Johnson Pumps 28512 is a direct-replacement marine pump cartridge designed to restore performance to 1000/1250 GPH cartridge pumps using a 12V motor.

This replacement cartridge is a precisely manufactured component intended for Johnson Pumps and compatible cartridge-style bilge and livewell pumps. It lets you replace the internal pump cartridge without changing the entire housing, saving time and cost while returning the pump to near-original flow performance. The cartridge is black, universal-fit rated for pumps advertised at 1000 or 1250 gallons per hour, and packaged compactly for straightforward installation.

How will this cartridge fit my existing pump?

The 28512 cartridge is built to a universal-fit specification that matches the internal dimensions and electrical connections of many 1000 and 1250 GPH cartridge pumps. Before ordering, compare your current cartridge’s model number and physical measurements to ensure compatibility. If dimensions and terminals match, the swap is typically plug-and-play.

• Compatible with 1000 and 1250 GPH cartridge-style pump housings
• 12V electrical design to match standard marine wiring
• Compact package: 7.5" L x 6" W x 3" H for easy handling
• Universal-fit approach reduces the need for a complete pump replacement

What performance can I expect after installing this cartridge?

Replacing a worn cartridge with the 28512 restores flow capacity and helps maintain consistent pump operation under normal marine conditions. Expect performance aligned with the original pump’s 1000–1250 GPH range when installed correctly and paired with an appropriate 12V motor and housing. Routine inspection of impeller and seals will help maintain those rates over time.

• Designed for 1000–1250 gallons per hour operating range
• 12V motor compatibility supports typical marine systems
• Replaces internal wear parts to reduce cavitation and loss of flow
• Helps restore original pump efficiency without new housing

How easy is installation and what should I check first?

Installation is straightforward for someone comfortable with basic marine electrical work: disconnect power, remove the pump housing, extract the old cartridge, and insert the new unit. Verify terminal types, orientation, and that seals or O-rings are seated properly to avoid leaks. Always reconnect power only after confirming the housing is closed and the wiring secure.

• Turn off and isolate 12V power before beginning
• Compare physical dimensions and terminals with the removed cartridge
• Inspect O-rings and replace if damaged to ensure watertight seal
• Test-run briefly to confirm correct rotation and flow

What maintenance will keep this cartridge lasting longer?

Periodic checks and simple maintenance extend the life of the cartridge: clear debris, ensure the impeller turns freely, and inspect electrical contacts for corrosion. Scheduling inspections at seasonal intervals or after heavy use prevents premature wear and reduces the chance of in-service failures. Replace the cartridge when signs of performance loss or physical damage appear.

• Inspect impeller and housing for debris buildup
• Check electrical connectors and clean corrosion as needed
• Replace O-rings and seals during cartridge swaps
• Monitor flow output to detect early performance decline

Who is this for: The Johnson Pumps 28512 cartridge suits boat owners, mariners, and maintenance technicians who want a reliable internal replacement for 1000/1250 GPH cartridge pumps operating on 12V systems. It is ideal when the pump housing is sound but internal components are worn, offering a cost-effective way to renew pump performance without installing a complete new unit.