Mercury In-Line Fuel Filter – Fits Mercury & Mariner 30–400HP 4-Stroke Outboards (Replaces 35-879885Q)

Mercury In-Line Fuel Filter – Fits Mercury & Mariner 30–400HP 4-Stroke Outboards (Replaces 35-879885Q)

This in-line fuel filter is designed for a wide range of Mercury and Mariner 4-Stroke outboard engines, including 30–40 HP EFI, 40–60 HP (996cc), 75–115 HP (1.7L), and 135–400 HP Verado models from 2004 and newer.

It serves as a direct replacement for Mercury part numbers 35-879885Q, 35-879885T, and 35-879885K, as well as Sierra part number 18-7718.

• Installation Type: Installs under the cowl, in-line with the fuel hose.
• Filtration: Provides 20-micron filtration to protect sensitive fuel system components.
• Connection: Fits standard 5/16" (7.9mm) fuel lines.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Mercury owners, here’s a guide to help you identify your engine’s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

Compatible Stern Drive Models

Technical Specifications

Package Contents

• 1 x In-Line Fuel Filter (Replaces 35-879885Q/35-879885T/35-879885K)

Installation Guide

1. Safety First: Turn off the engine and allow it to cool. Disconnect the negative battery terminal.
2. Locate Filter: Find the in-line fuel filter under the engine cowl, connected to the fuel line.
3. Prepare for Spills: Place a rag or container under the filter to catch any gasoline that may spill.
4. Remove Old Filter: Loosen the clamps securing the fuel hoses to both ends of the filter. Gently twist and pull the hoses off the filter barbs.
5. Note Fuel Flow: Pay close attention to the flow direction arrow on the old filter. The new filter must be installed in the same orientation.
6. Install New Filter: Attach the fuel hoses to the new filter, ensuring the arrow on the new filter housing points in the direction of fuel flow (towards the engine).
7. Secure Connections: Fasten the hose clamps securely on both ends of the new filter.
8. Check for Leaks: Reconnect the battery. Prime the fuel system by squeezing the primer bulb until firm. Start the engine and carefully inspect the filter and connections for any leaks.

Troubleshooting & FAQ

Q: How do I confirm this filter fits my engine?

A: Cross-reference your engine's model, year, and serial number with the compatibility tables above. For Mercury owners, we provide a Serial Number Guide to help. Verifying your existing part number against the cross-reference list is the most reliable method.

Q: How often should I replace my fuel filter?

A: For optimal engine health and performance, it is recommended to replace the fuel filter annually or every 100 hours of operation, whichever comes first. This interval can be shorter if you frequently use fuel of unknown quality.

Q: What are the signs of a clogged or failing fuel filter?

A: Common symptoms include difficulty starting, engine hesitation, stalling at low speeds, loss of power during acceleration, and inconsistent engine performance. The translucent housing allows for a visual check of trapped debris.

Q: OEM vs. Aftermarket?

A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?

A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?

A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.