Starter Solenoid – Fits Yamaha 25HP & Mercury 20HP 25HP 40HP 50HP 60HP 80HP 90HP (Replaces 65W-81941-00-00, 89-818997A1)

Product Details

This Starter Solenoid is designed to fit Yamaha 25HP engines and Mercury outboard motors ranging from 20HP to 90HP. Engineered as a direct replacement for OEM applications, this 12-volt solenoid features an isolated base with four terminals, ensuring reliable starting performance across a wide range of engine models from 1987 through 2005.

This part directly replaces Yamaha 65W-81941-00-00 and Mercury part numbers 89-818997A1, 89-818997A2, 89-818997T1, 89-818998A1, 89-818998A2, 89-850187A1, and 89-850187T1.

• Four-terminal configuration with isolated base for secure electrical connection
• Compatible with multiple Mercury outboard engine series from 20HP to 90HP
• Direct-fit replacement requiring no modifications

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Engine & Model Compatibility

Confirm your engine model/year in the table below.

Technical Specs

Voltage

12 Volts

Terminals

4 Terminals: (2) 1/4-20 Terminals, (2) 8-32 Terminals

Base Type

Isolated Base

What's in the Box

• 1 × Starter Solenoid

Installation Notes

1. Disconnect the negative battery cable to prevent accidental starting or electrical shock.
2. Locate the existing starter solenoid on your outboard engine, typically mounted near the starter motor.
3. Remove all electrical connections from the old solenoid, noting the position of each wire.
4. Unbolt the old solenoid from its mounting bracket and remove it.
5. Position the new solenoid in the same orientation and secure it with the mounting bolts.
6. Reconnect all wires to the corresponding terminals: larger 1/4-20 terminals for battery and starter motor cables, smaller 8-32 terminals for control wires.
7. Ensure all connections are tight and corrosion-free.
8. Reconnect the negative battery cable and test starter operation before returning to service.

Troubleshooting & FAQ

How do I know if my starter solenoid has failed?

Common symptoms include a clicking sound when turning the key with no engine cranking, intermittent starting issues, or no response at all when attempting to start. If the starter motor works when bypassed but not through the ignition key, the solenoid is likely faulty.

Will this fit my specific engine year and model?

Check the compatibility table above for your engine's horsepower and year range. Additionally, verify that your current solenoid matches the OEM part numbers listed. If your model year or HP falls within the specified ranges, this solenoid should fit.

What's the difference between the 1/4-20 and 8-32 terminals?

The two larger 1/4-20 terminals handle high-current connections from the battery and to the starter motor. The two smaller 8-32 terminals are for low-current control signals from the ignition switch. Always connect cables to the appropriately sized terminal.

Can I install this myself or do I need a mechanic?

Installation is straightforward for those with basic mechanical skills and tools. The process involves disconnecting the battery, removing four wire connections, swapping the solenoid, and reconnecting everything. If you're uncomfortable working with electrical systems, professional installation is recommended.

Why does my solenoid get hot during operation?

Some heat is normal during extended cranking. Excessive heat may indicate poor connections, corroded terminals, or a failing starter motor drawing too much current. Inspect all connections and ensure terminals are clean and tight.

How often should a starter solenoid be replaced?

Solenoids typically last many years under normal use. Replace when you experience starting failures, corrosion damage, or signs of electrical arcing. Marine environments accelerate wear due to moisture and salt exposure, so periodic inspection is advised.

Safety & Important Info

• Verify images/specifications against 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.