Fuel Filter – Mercury/Mariner 6–25 HP Replacement for 35-87946A3, 35-87946Q04 and 35-87946Q3
Fuel Filter – Mercury/Mariner 6–25 HP Replacement for 35-87946A3, 35-87946Q04 and 35-87946Q3 is backordered and will ship as soon as it is back in stock.
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Fuel Filter – Mercury/Mariner 6–25 HP Replacement for 35-87946A3, 3...
Fuel Filter – Mercury/Mariner 6–25 HP Replacement for 35-87946A3, 35-87946Q04 and 35-87946Q3 is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket fuel filter is a replacement for the Mercury/Mariner fuel filter identified by OEM references 35-87946A3, 35-87946Q04 and 35-87946Q3. The corresponding Sierra aftermarket reference is 18-7802.
Catalog information identifies this filter for Mercury/Mariner outboards from 6 HP through 25 HP. Because fitment can vary by engine configuration and serial-number range, compare the part number on your existing filter and verify the engine-specific parts catalog or service manual before ordering.
- Replacement fuel filter for selected Mercury/Mariner outboard fuel systems.
- Designed as a direct replacement for the listed reference numbers.
- Sold as a single fuel filter; this listing is not a filter-and-bowl kit.
Part Number Matrix
Use the following references to compare the replacement with the part listed for your engine.
| Brand or reference type | Part Number |
|---|---|
| Mercury/Mariner OEM reference | 35-87946A3 |
| Mercury/Mariner OEM reference | 35-87946Q04 |
| Mercury/Mariner OEM reference | 35-87946Q3 |
| Aftermarket reference | Sierra 18-7802 |
Engine & Model Compatibility
The available catalog relationship identifies the listed Mercury/Mariner fuel filter for 6 HP through 25 HP applications. The source does not establish one universal year range, stroke designation, or serial-number range for every engine in that horsepower range.
Before installation, confirm that your existing filter or engine parts information specifies one of the OEM references shown above. Do not rely on horsepower alone when the engine model or serial number is available.
| Brand | Application | Rated HP | Stroke | Reference | Verification note |
|---|---|---|---|---|---|
| Mercury/Mariner | Selected outboard applications | 6–25 HP | Verify by engine model and parts information | 35-87946A3, 35-87946Q04, 35-87946Q3 | Confirm the reference number before ordering. |
Technical Specifications
- Product Type
- Fuel filter
- Brand Application
- Mercury/Mariner
- Application Range
- Selected 6–25 HP outboard applications
- Aftermarket Reference
- Sierra 18-7802
- OEM References
- 35-87946A3, 35-87946Q04 and 35-87946Q3
- Product Format
- Single replacement filter
- Fuel
- Gasoline outboard fuel systems
What’s in the Box
- 1 x Fuel filter
No filter bowl, bowl assembly, or separately specified seal is identified as included with this product. Reuse only components that are serviceable and specified for your filter housing.
Installation Notes
- Stop the engine, allow it to cool, and disconnect the battery according to the engine service procedure.
- Work in a well-ventilated area away from flames, sparks, and ignition sources.
- Place an approved container or absorbent material beneath the filter to catch fuel.
- Close or isolate the fuel supply where the engine design permits.
- Remove the existing filter from the fuel system, noting the fuel-flow direction and hose orientation.
- Compare the replacement with the removed filter and confirm the part number before fitting it.
- Install the replacement filter in the same orientation and secure all connections according to the engine manufacturer's procedure.
- Restore the fuel supply and prime the system using the engine's normal priming method.
- Start the engine and inspect every connection carefully for fuel leakage.
- Stop immediately if leakage, fuel odor, restricted flow, or abnormal engine operation is observed.
Troubleshooting & FAQ
How do I confirm that this filter fits my engine?
Check the number on your existing filter or the engine parts catalog. This replacement is associated with Mercury/Mariner references 35-87946A3, 35-87946Q04 and 35-87946Q3, with Sierra 18-7802 as an aftermarket reference. Also confirm the engine model and serial-number range where applicable.
Does this filter fit every Mercury or Mariner engine from 6 to 25 HP?
Not necessarily. The catalog identifies a 6–25 HP application range, but horsepower alone does not establish every model, year, stroke configuration, or serial-number range. Verify the reference number and engine-specific parts information before ordering.
Is this a complete filter-and-bowl kit?
No. The company product record identifies this product as a single fuel filter. A bowl assembly and other housing components are not listed as included.
Is a replacement O-ring included?
A separately included O-ring is not identified in the company product record. Check the condition and service requirements of the existing seal and obtain the correct replacement separately if required by your engine's service procedure.
What are common signs of a restricted fuel filter?
Possible symptoms include hard starting, hesitation, sputtering, loss of power, rough running, or stalling under load. These symptoms can have several causes, so inspect the complete fuel system and follow the engine service manual before replacing parts.
Is this an OEM Mercury part?
No. This is an aftermarket replacement identified for the listed Mercury/Mariner OEM reference numbers. Mercury and Mariner are trademarks of their respective owners and are used only to describe application compatibility.
Safety & Important Information
- Verify the part number, filter configuration, engine model, and serial-number range before purchase and installation.
- Fuel is flammable. Use appropriate ventilation, protective equipment, and spill-control practices.
- Never operate the engine with a fuel leak or an improperly secured fuel connection.
- Professional installation is recommended when the correct procedure or fuel-system configuration is uncertain.
About Sea Sierra
- Marine Parts Selection — Replacement components for common marine maintenance needs.
- Application-Focused Listings — Reference numbers and compatibility details are provided to help you verify the correct part.
- Practical Maintenance Support — Always use the engine manufacturer's service information for model-specific installation and safety procedures.
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