{"product_id":"300-8m0077471-184-0003-ignition-coil-for-mercury-optimax-efi-jlm-marine","title":"300-8M0077471 184-0003 Ignition Coil for Mercury Optimax EFI | JLM Marine","description":"\u003ch2\u003eIgnition Coil for Mercury Optimax EFI – Fits Mercury 2-Stroke \u0026amp; 4-Stroke Outboard Motors\u003c\/h2\u003e\n\n\u003cp\u003eThis aftermarket ignition coil is engineered for \u003cstrong\u003eMercury Optimax, Mercury EFI 2-Stroke, Mercury EFI 4-Stroke, and Mercury Racing engines\u003c\/strong\u003e ranging from 30 HP to 300 HP. It delivers reliable spark and performance across a wide range of applications, including recreational, Pro XS, and racing models.\u003c\/p\u003e\n\n\u003cp\u003eDirect replacement for Mercury OEM part numbers \u003cstrong\u003e300-8M0077471\u003c\/strong\u003e, \u003cstrong\u003e184-0003\u003c\/strong\u003e, 300-879984T01, 339-879984A1, 339-879984T00, 879984T01, 8M00774714. Built to meet or exceed OEM specifications for dependable ignition across demanding marine conditions.\u003c\/p\u003e\n\n\u003cul\u003e\n\u003cli\u003eCompatible with Mercury Optimax, EFI 2-Stroke, EFI 4-Stroke, and Racing series engines\u003c\/li\u003e\n\u003cli\u003eDirect-fit replacement – no modifications required\u003c\/li\u003e\n\u003cli\u003eMeets or exceeds OEM performance standards\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003ePart Number Cross-Reference\u003c\/h2\u003e\n\n\u003cp\u003eUse this table to confirm equivalent part numbers across OEM and aftermarket brands.\u003c\/p\u003e\n\n\u003ctable border=\"1\" cellpadding=\"8\" cellspacing=\"0\"\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eBrand\u003c\/th\u003e\n\u003cth\u003ePart Number\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eMercury\u003c\/td\u003e\n\u003ctd\u003e300-8M0077471\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMercury\u003c\/td\u003e\n\u003ctd\u003e184-0003\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMercury\u003c\/td\u003e\n\u003ctd\u003e300-879984T01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMercury\u003c\/td\u003e\n\u003ctd\u003e339-879984A1\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMercury\u003c\/td\u003e\n\u003ctd\u003e339-879984T00\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMercury\u003c\/td\u003e\n\u003ctd\u003e879984T01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMercury\u003c\/td\u003e\n\u003ctd\u003e8M00774714\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003eCompatible Engine Models\u003c\/h2\u003e\n\n\u003cp\u003eConfirm your engine model\/year in the table below. For Mercury owners, here's a guide to help you identify your engine's serial\/model: \u003ca href=\"https:\/\/jlmmarine.com\/blogs\/serial-number-guide\/mercury-outboard-serial-number-guide\" target=\"_blank\" rel=\"nofollow noopener\"\u003eMercury Serial Number Guide\u003c\/a\u003e. You can also review exploded diagrams to verify part numbers: \u003ca href=\"https:\/\/jlmmarine.com\/blogs\/diagrams\/mercury-parts-catalog\" target=\"_blank\" rel=\"nofollow noopener\"\u003eMercury Parts Diagrams \u0026amp; Catalog\u003c\/a\u003e.\u003c\/p\u003e\n\n\u003cdiv style=\"overflow-x:auto;\"\u003e\n\u003ctable border=\"1\" cellpadding=\"8\" cellspacing=\"0\"\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eBrand\u003c\/th\u003e\n\u003cth\u003eModel\u003c\/th\u003e\n\u003cth\u003eRated HP\u003c\/th\u003e\n\u003cth\u003eStroke\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eMercury\u003c\/td\u003e\n\u003ctd\u003eEFI 4-Stroke\u003c\/td\u003e\n\u003ctd\u003e30, 40, 50, 60\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMercury\u003c\/td\u003e\n\u003ctd\u003eOptimax\u003c\/td\u003e\n\u003ctd\u003e75, 90, 115, 125, 200, 225, 250\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMercury\u003c\/td\u003e\n\u003ctd\u003eOptimax Pro XS\u003c\/td\u003e\n\u003ctd\u003e115 Pro, 175 Pro, 200 Pro, 225 Pro, 250 Pro\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMercury\u003c\/td\u003e\n\u003ctd\u003eOptimax Racing\u003c\/td\u003e\n\u003ctd\u003e225 XS, 225 Sport XS, 250 XS, 250 Sport XS, 300 XS\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMercury\u003c\/td\u003e\n\u003ctd\u003eEFI 2-Stroke\u003c\/td\u003e\n\u003ctd\u003e150 (2.5 EFI), 175 (2.5 EFI), 200 (2.5 EFI), 200 (3.0 EFI), 225 (3.0 EFI), 250 (3.0 EFI)\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMercury\u003c\/td\u003e\n\u003ctd\u003eRacing EFI 2-Stroke\u003c\/td\u003e\n\u003ctd\u003e225X, 300X\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\n\u003ctable border=\"1\" cellpadding=\"8\" cellspacing=\"0\"\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eSpecification\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eOEM Number\u003c\/td\u003e\n\u003ctd\u003e300-8M0077471, 184-0003\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType\u003c\/td\u003e\n\u003ctd\u003eIgnition Coil\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCompatibility\u003c\/td\u003e\n\u003ctd\u003eMercury Optimax, EFI 2-Stroke, EFI 4-Stroke, Racing series\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eApplication\u003c\/td\u003e\n\u003ctd\u003eDirect replacement for Mercury outboard motors\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003ePackage Contents\u003c\/h2\u003e\n\n\u003cul\u003e\n\u003cli\u003e\u003cspan style=\"color:red;\"\u003e1 × Ignition Coil\u003c\/span\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eInstallation Guide\u003c\/h2\u003e\n\n\u003col\u003e\n\u003cli\u003e\n\u003cstrong\u003eDisconnect the battery\u003c\/strong\u003e negative terminal to ensure safe working conditions. Confirm that the engine is off and cool to the touch.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLocate the ignition coil\u003c\/strong\u003e on your Mercury outboard motor. Refer to your engine's service manual or parts diagram if needed.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDisconnect the electrical connectors\u003c\/strong\u003e from the old ignition coil. Note the wire positions or take a photo for reference during reassembly.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove the mounting bolts\u003c\/strong\u003e securing the old coil to the engine block. Keep the hardware for reinstallation unless new fasteners are provided.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove the old ignition coil\u003c\/strong\u003e from the engine bay. Inspect the mounting area and clean any debris or corrosion.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePosition the new ignition coil\u003c\/strong\u003e in place, aligning the mounting holes with the engine block. Ensure proper orientation and seating.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall and tighten the mounting bolts\u003c\/strong\u003e to the manufacturer's recommended torque specification. Do not overtighten to avoid cracking the coil housing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReconnect the electrical connectors\u003c\/strong\u003e to the new ignition coil, ensuring each wire is fully seated and secure. Double-check all connections against your reference photo.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReconnect the battery\u003c\/strong\u003e negative terminal. Ensure all tools and materials are clear of the engine bay.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStart the engine\u003c\/strong\u003e and listen for smooth operation. Check for misfires, rough idle, or warning lights on the dashboard.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePerform a test run\u003c\/strong\u003e at low speed, then gradually increase throttle to verify proper ignition performance. Monitor engine temperature and RPM stability.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInspect all connections\u003c\/strong\u003e after the test run to confirm there are no loose wires or vibration-related issues. Recheck mounting bolt torque if necessary.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch2\u003eTroubleshooting \u0026amp; FAQ\u003c\/h2\u003e\n\n\u003cp\u003e\u003cstrong\u003eHow do I confirm this ignition coil fits my Mercury engine?\u003c\/strong\u003e\u003cbr\u003e\nCheck the Compatible Engine Models table above for your engine's horsepower, stroke type, and series (Optimax, EFI, Pro XS, Racing). Cross-reference your existing coil's part number with the Part Number Cross-Reference table to ensure compatibility.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhat are the signs that my ignition coil needs replacement?\u003c\/strong\u003e\u003cbr\u003e\nCommon symptoms include engine misfires, rough idling, difficulty starting, loss of power, poor fuel economy, and intermittent stalling. If you experience any of these issues, inspect the ignition coil for cracks, corrosion, or burnt connectors.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eHow often should I replace my ignition coil?\u003c\/strong\u003e\u003cbr\u003e\nIgnition coils do not have a fixed service interval and are typically replaced only when they fail. Regular inspection during seasonal maintenance is recommended, especially if you operate in saltwater or harsh conditions.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eCan I install this ignition coil myself, or do I need a professional?\u003c\/strong\u003e\u003cbr\u003e\nIf you have basic mechanical skills and tools, you can install this coil following the Installation Guide above. However, professional installation is recommended to ensure proper torque, electrical connections, and ignition timing verification.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhat's the difference between this aftermarket coil and the OEM Mercury part?\u003c\/strong\u003e\u003cbr\u003e\nThis is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eHow fast do you ship and how much does it cost?\u003c\/strong\u003e\u003cbr\u003e\nWe offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhat is your warranty and return policy?\u003c\/strong\u003e\u003cbr\u003e\nThis product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused \u0026amp; in original condition); please see our policy page or reach out for instructions.\u003c\/p\u003e\n\n\u003ch2\u003eImportant Notes\u003c\/h2\u003e\n\n\u003cul\u003e\n\u003cli\u003eVerify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.\u003c\/li\u003e\n\u003cli\u003eThis product is an aftermarket replacement part and is not an OEM component.\u003c\/li\u003e\n\u003cli\u003eProfessional installation is recommended to ensure safety and optimal performance.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhy Choose JLM MARINE?\u003c\/h2\u003e\n\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eQuality Assured:\u003c\/strong\u003e As a trusted manufacturer for over 20 years, we supply top marine brands globally.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFast Global Shipping:\u003c\/strong\u003e Free delivery worldwide in 5–15 days.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDirect from Manufacturer:\u003c\/strong\u003e Competitive pricing without compromising quality.\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"JLM Marine","offers":[{"title":"Default Title","offer_id":51981021118777,"sku":"24IC371","price":28.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0885\/0433\/6697\/files\/10_988a32ef-6cb5-481c-954c-d222f68540c8.jpg?v=1772448331","url":"https:\/\/jlmmarine.com\/ru\/products\/300-8m0077471-184-0003-ignition-coil-for-mercury-optimax-efi-jlm-marine","provider":"JLM Marine Boat Parts Limited","version":"1.0","type":"link"}