{"product_id":"6g9-85540-cdi-unit-for-yamaha-mercury-jlm-marine","title":"6G9-85540 CDI Unit for Yamaha Mercury | JLM Marine","description":"\u003ch2\u003eCDI Unit for Yamaha Mercury 4-Stroke Outboard 8HP 9.9HP | Direct Replacement for 6G9-85540\u003c\/h2\u003e\n\n\u003cp\u003eThis aftermarket CDI (Capacitor Discharge Ignition) unit is engineered to fit \u003cstrong\u003eYamaha 9.9 HP 2-cylinder engines (1985–2005)\u003c\/strong\u003e and \u003cstrong\u003eMercury\/Mariner 8 HP and 9.9 HP 2-cylinder 4-stroke outboards (1995–2000)\u003c\/strong\u003e. It delivers reliable ignition performance across a wide range of model years for both brands.\u003c\/p\u003e\n\n\u003cp\u003eThis unit directly replaces \u003cstrong\u003eYamaha 6G9-85540-20-00, 6G9-85540-21-00, 6G9-85540-22-00, 6G9-85540-29-00\u003c\/strong\u003e, and \u003cstrong\u003eMercury 825667, 825667T\u003c\/strong\u003e, ensuring seamless compatibility with your existing electrical system.\u003c\/p\u003e\n\n\u003cul\u003e\n  \u003cli\u003eFits both Yamaha and Mercury 2-cylinder 4-stroke outboards\u003c\/li\u003e\n  \u003cli\u003eDirect plug-and-play replacement for OEM ignition packs\u003c\/li\u003e\n  \u003cli\u003eCovers multiple model years from mid-1980s to mid-2000s\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\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\u003eYamaha\u003c\/td\u003e\n      \u003ctd\u003e6G9-85540\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eYamaha\u003c\/td\u003e\n      \u003ctd\u003e6G9-85540-22\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eYamaha\u003c\/td\u003e\n      \u003ctd\u003e6G9-85540-20-00\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eYamaha\u003c\/td\u003e\n      \u003ctd\u003e6G9-85540-21-00\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eYamaha\u003c\/td\u003e\n      \u003ctd\u003e6G9-85540-22-00\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eYamaha\u003c\/td\u003e\n      \u003ctd\u003e6G9-85540-29-00\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eMercury\u003c\/td\u003e\n      \u003ctd\u003e825667\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eMercury\u003c\/td\u003e\n      \u003ctd\u003e825667T\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 Yamaha owners, here's a guide to help you identify your engine's serial\/model: \u003ca href=\"https:\/\/jlmmarine.com\/blogs\/serial-number-guide\/yamaha-outboard-serial-number-guide-2025\" rel=\"nofollow noopener\" target=\"_blank\"\u003eYamaha Serial Number Guide\u003c\/a\u003e. You can also review exploded diagrams to verify part numbers: \u003ca href=\"https:\/\/jlmmarine.com\/blogs\/serial-number-guide\/yamaha-outboard-parts-diagrams-catalog\" rel=\"nofollow noopener\" target=\"_blank\"\u003eYamaha Parts Diagrams \u0026amp; Catalog\u003c\/a\u003e.\u003c\/p\u003e\n\n\u003cp\u003eFor 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\" rel=\"nofollow noopener\" target=\"_blank\"\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\" rel=\"nofollow noopener\" target=\"_blank\"\u003eMercury Parts Diagrams \u0026amp; Catalog\u003c\/a\u003e.\u003c\/p\u003e\n\n\u003cdiv style=\"overflow-x:auto;\"\u003e\n  \u003ctable\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth\u003eBrand\u003c\/th\u003e\n        \u003cth\u003eRated HP\u003c\/th\u003e\n        \u003cth\u003eStroke\u003c\/th\u003e\n        \u003cth\u003eYears\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eYamaha\u003c\/td\u003e\n        \u003ctd\u003e9.9 HP\u003c\/td\u003e\n        \u003ctd\u003e2-Cylinder\u003c\/td\u003e\n        \u003ctd\u003e1985–2005\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury\/Mariner\u003c\/td\u003e\n        \u003ctd\u003e8 HP\u003c\/td\u003e\n        \u003ctd\u003e2-Cylinder 4-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1995–2000\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury\u003c\/td\u003e\n        \u003ctd\u003e9.9 HP\u003c\/td\u003e\n        \u003ctd\u003e2-Cylinder\u003c\/td\u003e\n        \u003ctd\u003e1995–1998\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\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\u003eProduct Type\u003c\/td\u003e\n      \u003ctd\u003eCDI Unit (Capacitor Discharge Ignition)\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eCompatibility\u003c\/td\u003e\n      \u003ctd\u003eYamaha 9.9 HP 2-Cylinder (1985–2005), Mercury\/Mariner 8 HP \u0026amp; 9.9 HP 2-Cylinder 4-Stroke (1995–2000)\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eOEM Replacement\u003c\/td\u003e\n      \u003ctd\u003eYamaha 6G9-85540 series, Mercury 825667\/825667T\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 × CDI Unit for Yamaha Mercury 4-Stroke Outboard 8HP 9.9HP\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 Remove the negative cable to ensure all electrical power is off before beginning work.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLocate the existing CDI unit:\u003c\/strong\u003e It is typically mounted near the engine block or under the cowling. Consult your service manual if unsure.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDisconnect wiring harness:\u003c\/strong\u003e Carefully unplug all connectors from the old CDI unit. Note the wire colors and positions for reference.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRemove mounting hardware:\u003c\/strong\u003e Unbolt or unclip the old CDI unit from its bracket.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eInstall the new CDI unit:\u003c\/strong\u003e Position the replacement unit in the same location and secure it with the original mounting hardware.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eReconnect wiring harness:\u003c\/strong\u003e Attach all connectors to the new CDI unit, ensuring each plug is fully seated and secure.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eReconnect the battery:\u003c\/strong\u003e Reattach the negative cable and ensure all connections are tight.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eTest the ignition system:\u003c\/strong\u003e Turn the key to the ON position and attempt to start the engine. Verify smooth ignition and consistent running.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCheck for error codes:\u003c\/strong\u003e If your engine has a diagnostic system, confirm no fault codes are present.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePerform a sea trial:\u003c\/strong\u003e Run the engine at various RPMs to ensure stable performance and proper timing under load.\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 CDI unit fits my engine?\u003c\/strong\u003e\u003cbr\u003e\nCheck the compatibility table above for your engine's brand, HP, and year range. Cross-reference your original part number (6G9-85540 series for Yamaha or 825667\/825667T for Mercury) to ensure a match.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhat are the signs that my CDI unit is failing?\u003c\/strong\u003e\u003cbr\u003e\nCommon symptoms include hard starting, intermittent misfires, loss of power at high RPM, or complete failure to spark. If you've ruled out spark plugs and coils, the CDI unit is often the next component to check.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eHow often should I replace the CDI unit?\u003c\/strong\u003e\u003cbr\u003e\nCDI units typically last many years under normal use. Replace only if you experience ignition problems or if diagnostics point to CDI failure. There is no fixed maintenance interval.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWill this aftermarket CDI perform the same as the OEM unit?\u003c\/strong\u003e\u003cbr\u003e\nYes. This unit is built to OEM specifications and delivers equivalent ignition performance. It is tested to ensure reliable spark timing and durability across the full RPM range.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eCan I install this CDI unit myself?\u003c\/strong\u003e\u003cbr\u003e\nIf you have basic mechanical and electrical skills, installation is straightforward—disconnect the old unit, swap in the new one, and reconnect the wiring. However, professional installation is recommended to avoid incorrect wiring or damage.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eOEM vs. Aftermarket?\u003c\/strong\u003e\u003cbr\u003e\nThis listing 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":51960671764793,"sku":"18CD001","price":48.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0885\/0433\/6697\/files\/12_8ddac035-13ec-4533-9c88-c73324a88aa0.jpg?v=1771677659","url":"https:\/\/jlmmarine.com\/es\/products\/6g9-85540-cdi-unit-for-yamaha-mercury-jlm-marine","provider":"JLM Marine Boat Parts Limited","version":"1.0","type":"link"}