7" Spark Plug Wire – Fits Mercury Marine 150-200 HP Outboard Motors (Replaces 18-8819, 813715A1, 90816A25)
7" Spark Plug Wire – Fits Mercury Marine 150-200 HP Outboard Motors (Replaces 18-8819, 813715A1, 90816A25) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
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7" Spark Plug Wire – Fits Mercury Marine 150-200 HP Outboard M...
7" Spark Plug Wire – Fits Mercury Marine 150-200 HP Outboard Motors (Replaces 18-8819, 813715A1, 90816A25) is backordered and will ship as soon as it is back in stock.
Product Details
This high-performance 7" Spark Plug Wire is a direct-fit replacement for Mercury Marine 150-200 HP V6 outboard motors manufactured between 1970 and 1988, including V-150, V-175, and V-200 series engines. Engineered for reliability in harsh marine environments, it ensures a stable and powerful connection for optimal ignition performance.
It serves as a direct interchange for Sierra part number 18-8819 and numerous Mercury OEM numbers, ensuring a precise match for your engine's ignition system. This part is ideal for routine maintenance or for resolving ignition-related issues.
- Simple direct replacement installation with no modification required.
- Marine-grade construction resists heat, saltwater corrosion, vibration, and fuel exposure.
- Note: Different wire lengths (5", 9", 12") are available for these engines depending on the specific cylinder position.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket brands.
| Brand | Part Number |
|---|---|
| Sierra | 18-8819 |
| Mercury | 813715A1 |
| Mercury | 90816A25 |
| Mercury | 93475A25 |
| Mercury | 99215A25 |
| Mercury | 99215A29 |
| Mercury | 20114A2 |
| Mercury | 20122A2 |
| Mercury | 23564A4 |
| Mercury | 23564A5 |
| Mercury | 23564A6 |
| Mercury | 23564A8 |
| Mercury | 23564A9 |
| Mercury | 26453A1 |
| Mercury | 26460A1 |
| Mercury | 47899A9 |
| Mercury | 63212A2 |
| Mercury | 697331 |
| Mercury | 70668 |
| Mercury | 73451A8 |
| Mercury | 762238 |
Engine & Model Compatibility
Confirm your engine model and year in the table below. Verifying the OEM part number and serial range for your specific application is crucial for ensuring a correct fit.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | V-150 | 150 | 2-Stroke | 1970–1988 | 813715A1, 90816A25 | Serial range: 4868998-0A904645 |
| Mercury | V-150 Magnum | 150 | 2-Stroke | 1970–1988 | 813715A1, 90816A25 | Serial range: 5600162-0A904645 |
| Mercury | V-150 Marathon | 150 | 2-Stroke | 1970–1988 | 813715A1, 90816A25 | Serial range: 5600162-0A904645 |
| Mercury | V-150 Work | 150 | 2-Stroke | 1970–1988 | 813715A1, 90816A25 | Serial range: 4868998-0A904645 |
| Mercury | V-150-XR-2 | 150 | 2-Stroke | 1970–1988 | 813715A1, 90816A25 | Serial range: 4868998-0A904645 |
| Mercury | V-1500 | 150 | 2-Stroke | 1970–1988 | 813715A1, 90816A25 | Serial range: 4868998-0A904645 |
| Mercury | V-175 | 175 | 2-Stroke | 1970–1988 | 813715A1, 90816A25 | Serial range: 4301235-0C100860, 8058870-UP |
| Mercury | V-200 | 200 | 2-Stroke | 1970–1988 | 813715A1, 90816A25 | Serial range: 5239232-0C100860 |
Technical Specs
- Product Type
- Spark Plug Wire
- Installation
- Direct replacement
- Length
- 7 inches (178 mm)
- Compatible With
- Mercury Marine outboard engines
- Material
- Silicone insulation with stainless steel components
- Connection Type
- Terminal end connects to coil/distributor, boot end connects to spark plug
- Color
- Black
- Warranty
- 1 Year (retailer dependent)
- Other Technical Attributes
- Marine-grade construction resistant to heat, saltwater corrosion, vibration, and fuel exposure
What’s in the Box
- 1 x 7" Spark Plug Wire (Replaces 813715A1, 90816A25)
Installation Notes
- Safety First: Before starting, disconnect the boat's battery to prevent electrical shock.
- One at a Time: To avoid mixing up firing order, replace one spark plug wire at a time. Start with the first cylinder.
- Remove Old Wire: Firmly grip the spark plug boot, twist slightly, and pull it straight off the spark plug. Do the same on the distributor/coil end.
- Compare and Match: Before installing, compare the new wire to the old one to ensure the length and boot angles match.
- Install New Wire: Lightly apply dielectric grease to the inside of both boots. Push the new wire's boot firmly onto the spark plug until you feel it click into place. Repeat for the distributor/coil end.
- Final Check: Once all wires are replaced, reconnect the battery and start the engine to ensure it runs smoothly.
Troubleshooting & FAQ
How do I know this 7" wire is the correct length for my engine?
This 7-inch wire is designed for specific cylinder positions on the listed Mercury V6 engines. Different cylinders may require different lengths (e.g., 5", 9", 12"). Always measure your existing wire or consult your engine's service manual to confirm you are ordering the correct length for the cylinder you are servicing.
What are the signs of a bad spark plug wire?
Common symptoms of a failing spark plug wire include a rough idle, engine misfires (especially under load), decreased fuel economy, and visible signs of damage like cracks, burns, or corrosion on the wire or boots.
How does this aftermarket wire compare to an OEM Mercury part?
This wire is built to meet or exceed OEM specifications for fit, material quality, and performance. It is made with high-quality silicone insulation and stainless steel terminals, just like the original, to provide reliable conductivity and long life in marine conditions.
What is the recommended replacement interval for spark plug wires?
It is good practice to inspect spark plug wires annually for any signs of wear or damage. A general recommendation is to replace them every 3-5 years or as part of a major ignition system tune-up, depending on usage and a-environmental conditions.
Can I install just one wire, or should I replace the whole set?
While you can replace a single faulty wire, it is generally recommended to replace all spark plug wires as a complete set. This ensures consistent performance, resistance, and age across the entire ignition system, preventing future issues with the older wires.
The connection seems loose. What should I do?
Ensure you have pushed the boot onto the spark plug and distributor/coil terminal firmly. You should feel or hear a distinct "click" as it snaps into place. A light coating of dielectric grease inside the boot can help with seating and sealing.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
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