Sierra Power Pack 18-99251 for Johnson/Evinrude 4-Cylinder 120/140 HP and 8-Cylinder 275/300 HP Outboards (1985)

The Sierra 18-99251 is a CD ignition power pack built for Johnson/Evinrude outboards, covering both 4-cylinder and 8-cylinder engine configurations. It supplies the capacitor discharge ignition energy that fires the spark plugs, and is a core component of the engine's ignition system, replacing a worn or failed power pack to restore reliable starting and running performance.

The unit is housed in a black plastic enclosure rated waterproof, suited to the marine environment. It connects through a proprietary 3-pin main power connector and runs on an AC power source, matching the factory ignition wiring on the covered engines. The compact, sealed design is built to hold up to engine bay vibration, heat, and moisture exposure over time.

This power pack is compatible with Johnson/Evinrude 1985 120 HP and 140 HP 4-cylinder outboards, as well as 275 HP and 300 HP 8-cylinder outboards. It is a direct fit for these specific engine and horsepower combinations, so confirm your engine's model year and horsepower rating before ordering.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-99251
• Compatible Engines: Johnson/Evinrude 1985 120 HP and 140 HP (4-cylinder), 275 HP and 300 HP (8-cylinder) outboards
• Cylinder Configuration: 4-cylinder and 8-cylinder
• Connector Type: Proprietary
• Main Power Connector Type: 3 Pin
• Power Source: AC
• Material: Plastic
• Color: Black
• Special Feature: Waterproof
• Weight: 0.9 pounds

Fitment

• Johnson/Evinrude 1985 120 HP and 140 HP outboards (4-cylinder)
• Johnson/Evinrude 1985 275 HP and 300 HP outboards (8-cylinder)

Replaces (OEM)

• 113-3072

Frequently Asked Questions

What engines does the Sierra 18-99251 power pack fit? The 18-99251 fits Johnson/Evinrude 1985 outboards rated 120 HP and 140 HP on 4-cylinder engines, and 275 HP and 300 HP on 8-cylinder engines.

Does 18-99251 cross-reference to any other part number? Yes, Sierra part 18-99251 replaces OEM part number 113-3072.

What does this power pack actually do? It is a capacitor discharge (CD) ignition component that generates and delivers the spark energy needed to fire the spark plugs on the covered Johnson/Evinrude outboards.

Is the 18-99251 power pack waterproof? Yes, this power pack is rated waterproof, which suits its use in a marine engine environment.

What color and material is the housing? The 18-99251 power pack has a black plastic enclosure.

How much does the 18-99251 power pack weigh? It weighs 0.9 pounds.

What type of electrical connection does this power pack use? The 18-99251 uses a proprietary 3-pin main power connector and runs on an AC power source.

Will the 18-99251 power pack work on outboards other than the listed 4-cylinder and 8-cylinder models? This power pack is confirmed to fit Johnson/Evinrude 1985 120/140 HP 4-cylinder and 275/300 HP 8-cylinder outboards; fitment for other engines is not specified.

Does one power pack cover both the 4-cylinder and 8-cylinder engines? Yes, Sierra 18-99251 is designed to cover both the 4-cylinder (120/140 HP) and 8-cylinder (275/300 HP) Johnson/Evinrude engine configurations.

Is 18-99251 a new replacement unit? Yes, the 18-99251 is a replacement power pack for Johnson/Evinrude 4/8-cylinder outboards, not a rebuilt or used unit.