3H9-70311-0 Fuel Tap Cock Switch for Tohatsu Mercury MFS4A2 MFS4B MFS4C MFS5A2 MFS5B MFS5C MFS6A2 MFS6B MFS6C | JLM Marine

Fuel Tap Cock Switch – Fits Tohatsu Mercury 4HP 5HP 6HP Outboard Motors

This fuel tap cock switch is designed for Tohatsu and Mercury 4-stroke outboard engines ranging from 4HP to 6HP. It provides reliable fuel flow control for your engine, ensuring smooth operation and easy maintenance. Compatible with multiple engine series including MFS4A2, MFS4B, MFS4C, MFS5A2, MFS5B, MFS5C, MFS6A2, MFS6B, and MFS6C models.

This switch directly replaces OEM part number 3H9-70311-0 and its variants, delivering dependable performance for your outboard motor's fuel system.

• Precision-engineered for Tohatsu and Mercury 4-stroke outboards
• Direct replacement for OEM fuel cock assembly
• Essential component for fuel system control and maintenance

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.

Technical Specifications

Package Contents

Your package includes:

• 1 × Fuel Cock Assy Switch

Installation Guide

1. Ensure the engine is completely off and cool before beginning work. Disconnect the fuel line from the existing fuel cock assembly.
2. Remove the mounting screws or fasteners securing the old fuel tap cock switch to the engine. Carefully extract the old unit.
3. Inspect the mounting surface and fuel line connections for debris or damage. Clean as necessary to ensure proper seal.
4. Position the new fuel tap cock switch in the correct orientation, aligning the fuel inlet and outlet ports with your fuel lines.
5. Secure the new switch using the original mounting hardware or provided fasteners. Tighten evenly to manufacturer specifications.
6. Reconnect the fuel line to the new fuel cock assembly, ensuring all connections are snug and leak-free.
7. Turn the fuel cock to the "ON" position and check for any fuel leaks around the connections and mounting points.
8. Start the engine and let it run for a few minutes while monitoring for proper fuel flow and any signs of leakage.

Troubleshooting & FAQ

Q: How do I confirm this fuel tap cock switch fits my Tohatsu or Mercury outboard?
A: Check the Compatible Engine Models table above for your specific model number (e.g., MFS4B, MFS5C, MFS6A2). Also verify that your original part number matches 3H9-70311-0, 3H9703110, or 3H9703110M to ensure compatibility.

Q: What are the signs that my fuel cock switch needs replacement?
A: Common symptoms include fuel leaks around the switch assembly, difficulty turning the fuel valve, inconsistent fuel flow to the engine, or visible cracks and wear on the switch body. If you notice any of these issues, replacement is recommended.

Q: How often should I inspect or replace this fuel tap cock switch?
A: Inspect the fuel cock switch annually as part of your regular outboard maintenance routine. Replace it immediately if you notice any leaks, cracks, or operational issues, or every 5-7 years as a preventive measure depending on usage and exposure to the elements.

Q: Can I install this switch myself or do I need a professional?
A: Installation is straightforward for those with basic mechanical skills and tools. However, because it involves fuel system components, professional installation is recommended to ensure proper sealing and safety, especially if you're unfamiliar with outboard fuel systems.

Q: Is this an OEM part or aftermarket replacement?
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.