Sierra Fuel Water Separator Filter 18-7989, 10 Micron Cobra EFI, Replaces OMC 502906

The Sierra 18-7989 is a 10 micron fuel water separator filter built for Cobra EFI fuel systems. It is designed as a direct replacement for OMC 502906, giving boat owners a straightforward way to keep water and contaminants out of the fuel system without altering the original fuel line setup. The filter media rates at 10 microns, providing a finer level of filtration suited to electronic fuel injection systems that are more sensitive to contamination than carbureted engines.

The housing uses a plastic outer material and connects via a 13/16-18 thread pitch, matching the OMC Cobra EFI mounting configuration. As a spin-on style filter, it is intended to be threaded onto the existing filter head or bracket and replaced as part of routine fuel system maintenance. Keeping this filter fresh helps protect fuel injectors and other EFI components from water intrusion and particulate damage, which is especially important in marine environments where condensation and fuel quality issues are common.

Every Sierra part is backed by the company's standard customer satisfaction warranty, so buyers replacing a Cobra EFI fuel filter can install the 18-7989 with confidence that it matches OEM specifications for fit and filtration performance.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-7989
• Micron Rating: 10 Micron
• Filter Type: Cobra EFI
• Thread Pitch: 13/16-18
• Outer Material: Plastic
• Weight: 0.69 pounds
• OEM Cross Reference: OMC 502906
• UPC: 808282201883

Fitment

Fits OMC Cobra EFI fuel systems using the 502906 style fuel water separator filter.

Replaces (OEM)

• OMC 502906

Frequently Asked Questions

What does the Sierra 18-7989 replace? The Sierra 18-7989 is a direct replacement for OMC 502906, the original fuel water separator filter used on OMC Cobra EFI fuel systems.

What micron rating is this filter? It is rated at 10 microns, which is the standard filtration level for the Cobra EFI version of this Sierra fuel water separator filter.

What thread size does the 18-7989 use? This filter has a 13/16-18 thread pitch, matching the mounting thread used on OMC Cobra EFI filter heads.

Is the 18-7989 an OEM or aftermarket part? The 18-7989 is a Sierra-manufactured replacement filter engineered to match the fit and filtration performance of OEM part OMC 502906.

What is the filter housing made of? The outer housing of the Sierra 18-7989 fuel water separator filter is made of plastic.

How much does this filter weigh? The Sierra 18-7989 fuel water separator filter weighs 0.69 pounds.

Will this filter fit a standard fuel filter thread instead of the Cobra EFI version? No, the 18-7989 is built specifically for the Cobra EFI thread configuration; Sierra offers separate part numbers, such as 18-7946, for OMC thread applications.

Does the 18-7989 come with a warranty? Yes, the Sierra 18-7989 is covered under Sierra's standard customer satisfaction warranty like all Sierra parts.

What is included when I order the 18-7989? Ordering the 18-7989 includes one Sierra fuel water separator filter designed for Cobra EFI systems.

How is the 21 micron version different from the 18-7989? The 18-7989 is the 10 micron Cobra EFI filter, while the 21 micron equivalent for the same Cobra EFI application is a different Sierra part number with coarser filtration.

Why does fuel filtration matter on an EFI system? Electronic fuel injection systems like those served by the 18-7989 are more sensitive to water and debris than carbureted engines, so a properly rated 10 micron filter helps protect injectors from contamination.