Sierra Voltage Regulator 18-99434 for Mercury 135-225 HP 6-Cylinder Outboards 1981-1993, Replaces 88825A7

The Sierra 18-99434 is a 16-amp voltage regulator built for 6-cylinder Mercury outboard engines. It regulates charging output to the battery, protecting the electrical system from overcharging while keeping the battery topped off during operation. The regulator is housed in a waterproof plastic enclosure finished in black, designed to withstand the marine environment where it is mounted on the outboard.

Electrically, the unit outputs 12 volts DC at up to 16 amps and connects to the existing engine harness through a 2-pin connector, making it a straightforward swap for a failed or worn regulator. It is built to fit Mercury outboard engines rated 135, 150, 175, 200, and 225 HP from 1981-1993, and is a direct replacement for the OEM Mercury voltage regulators it supersedes.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-99434
• Category: Mercury Outboard Voltage Regulator
• Engine Cylinder Configuration: 6-Cylinder
• Amperage: 16 Amps
• Output Voltage: 12 Volts (DC)
• Connector Type: 2-Pin
• Material: Plastic
• Color: Black
• Special Feature: Waterproof
• Weight: 0.8 pounds
• UPC: 808282394653

Fitment

• Mercury outboard engines, 135, 150, 175, 200, and 225 HP, 1981-1993, 6-cylinder

Replaces (OEM)

• 194-8825K1
• 88825A1
• 88825A7

Frequently Asked Questions

What engines does the Sierra 18-99434 voltage regulator fit? It fits Mercury outboard engines rated 135, 150, 175, 200, and 225 HP from 1981-1993, and is built for 6-cylinder configurations.

Does the Sierra 18-99434 replace OEM part 88825A7? Yes, the 18-99434 is a direct replacement for OEM Mercury voltage regulators 194-8825K1, 88825A1, and 88825A7.

What is the amperage output of this voltage regulator? The Sierra 18-99434 delivers a 16-amp charging output to the battery.

What voltage does the 18-99434 regulator put out? It outputs 12 volts DC, matching standard marine 12-volt charging systems.

Is the Sierra 18-99434 waterproof? Yes, it is built with a waterproof housing suited to the marine environment it operates in.

What is the housing material and color of the 18-99434? The regulator has a black plastic enclosure.

How much does the Sierra 18-99434 voltage regulator weigh? It weighs 0.8 pounds.

What type of connector does this voltage regulator use? The 18-99434 uses a 2-pin connector that plugs into the existing engine wiring harness.

Will the 18-99434 fit a 4-cylinder Mercury outboard? No, this regulator is designed for 6-cylinder Mercury outboard engines in the 135-225 HP range from 1981-1993, not 4-cylinder models.

Is the Sierra 18-99434 equivalent to the OEM Mercury regulator? Yes, the 18-99434 is a direct-fit equivalent to OEM Mercury regulators 194-8825K1, 88825A1, and 88825A7, offering the same 16-amp, 12-volt output.