WLFINKMO Ignition Coil for Mercury Optimax & Pro XS 75–250 HP — Single Unit Direct Replacement

WLFINKMO ignition coil for Mercury Optimax and EFI outboards delivers a high-intensity spark designed to restore reliable starting and steady throttle response. This replacement ignition coil fits a wide range of Mercury Marine Optimax, Pro XS, Racing and EFI 2- and 4-stroke engines, including popular HP ranges from 30 up to 300 depending on model. Built to replace OEM part numbers like 300-879984T01, 300-8M0077471 and 339-879984A1, this coil is intended as a direct swap to revive ignition performance without complex rewiring. It comes as a single unit and is aimed at owners and technicians who need a straightforward, cost-effective ignition component for common Mercury outboard platforms.

Which Mercury engines will this coil fit?

This coil is compatible with many Mercury Optimax, Pro XS, Racing and EFI models across 2- and 4-stroke families. Check your engine's model and the OEM replacement numbers before ordering to confirm fitment.

• Optimax: 75, 90, 115, 125, 175, 200, 225, 250 HP ranges
• Pro XS/Pro: 115 Pro, 175 Pro, 200 Pro, 225 Pro, 250 Pro
• Racing and Sport XS: 225 XS, 225 Sport XS, 250 XS, 250 Sport XS, 300 XS
• EFI 4-stroke: 30, 40, 50, 60 HP and EFI 2-stroke: 150–250 models noted

How does this ignition coil affect starting and performance?

The coil delivers increased ignition energy and faster spark recovery compared with a worn stock coil, which helps engines start more readily and maintain smoother acceleration. It doesn’t change engine tuning but supports more consistent combustion when paired with properly functioning fuel and ignition systems.

• Higher intensity spark for improved ignition of the air/fuel mix
• Faster response reduces misfires and hesitation under load
• Direct replacement avoids modifying existing wiring or mounts

Is installation difficult and what comes in the package?

Installation is intended to be a simple replacement of the existing coil unit—no additional parts are included or usually required. The package contains one ignition coil; reuse of existing fasteners and connectors is typical, but inspect mounting hardware and boots for wear during replacement.

• Package includes: 1 ignition coil (single unit)
• Replaces OEM numbers such as 300-879984T01 and 339-879984A1
• Installers should verify connector compatibility and torque specs

What should you check before buying a replacement coil?

Confirming engine compatibility and OEM replacement numbers is the most important step to avoid returns. Also inspect related ignition components—spark plugs, boots, wiring and the stator—because old or damaged parts can mask performance issues even after installing a new coil.

• Match part numbers: 300-8M0077471, 879984T01, 339-879984T00, etc.
• Inspect spark plugs and ignition leads for wear or corrosion
• Confirm mounting points and connector style before installation

Who is this for This WLFINKMO ignition coil is aimed at boat owners, marine technicians and performance tuners working with Mercury Optimax, Pro XS and EFI outboards who need a reliable, plug-and-play replacement. It’s useful when diagnosing tough starting, intermittent misfires or weak throttle response so long as the rest of the ignition and fuel systems are in good condition. If you require an exact fit, cross-check your engine model and OEM numbers listed in the product description before purchase to ensure compatibility.

FAQ

Q: Does this coil replace OEM 300-879984T01?

A: Yes. This WLFINKMO coil is listed as a replacement for 300-879984T01 and several related OEM numbers.

Q: Will I need extra parts to install it?

A: Usually no. The unit is a direct replacement, but inspect and possibly reuse existing boots, fasteners and wiring.