{"product_id":"vst-float-chamber-gasket-fits-mercury-mariner-yamaha-150hp-300hp-replaces-65l-14984-00-18-0715-809086","title":"VST Float Chamber Gasket – Fits Mercury Mariner Yamaha 150HP-300HP (Replaces 65L-14984-00, 18-0715, 809086)","description":"\u003cstyle\u003e\n  .ss-table-wrap { overflow-x:auto; -webkit-overflow-scrolling:touch; }\n  table.ss-table { width:100%; border-collapse:collapse; min-width:640px; }\n  table.ss-table th, table.ss-table td {\n    padding:10px 12px; border:1px solid #e5e7eb; text-align:left; vertical-align:top;\n  }\n  table.ss-table th {\n    white-space:nowrap;\n    word-break:normal;\n    letter-spacing:normal;\n    font-weight:600;\n    background:#f8fafc;\n  }\n  @media (max-width:480px){\n    table.ss-table th, table.ss-table td { padding:8px 10px; font-size:14px; }\n  }\n\u003c\/style\u003e\n\n\u003ch2\u003eProduct Details\u003c\/h2\u003e\n\u003cp\u003eThis VST Float Chamber Gasket fits Mercury, Mariner, and Yamaha outboard engines from 150HP to 300HP. Designed for Yamaha 6-cylinder 76-degree V200, V225, S225, and S250 models from 1997–1998, this gasket ensures a proper seal for your VST (Vapor Separator Tank) float chamber.\u003c\/p\u003e\n\u003cp\u003eDirect replacement for OEM part numbers 65L-14984-00, 65L-14984-00-00, 18-0715, 809086, and 25-809086.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003ePrecision-cut O-ring design for VST float chamber sealing\u003c\/li\u003e\n  \u003cli\u003eCompatible with Mercury, Mariner, and Yamaha fuel systems\u003c\/li\u003e\n  \u003cli\u003eEssential component for preventing fuel leaks and maintaining proper fuel pressure\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003ePart Number Matrix\u003c\/h2\u003e\n\u003cp\u003eUse this matrix to confirm equivalent references across OEM and aftermarket.\u003c\/p\u003e\n\u003cdiv class=\"ss-table-wrap\"\u003e\n  \u003ctable class=\"ss-table\" aria-label=\"Part Number Matrix\"\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\u003e65L-14984-00\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eYamaha\u003c\/td\u003e\n        \u003ctd\u003e65L-14984-00-00\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eSierra\u003c\/td\u003e\n        \u003ctd\u003e18-0715\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury\u003c\/td\u003e\n        \u003ctd\u003e809086\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury\u003c\/td\u003e\n        \u003ctd\u003e25-809086\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eEngine \u0026amp; Model Compatibility\u003c\/h2\u003e\n\u003cp\u003eConfirm your engine model\/year in the table below.\u003c\/p\u003e\n\u003cdiv class=\"ss-table-wrap\"\u003e\n  \u003ctable class=\"ss-table\" aria-label=\"Engine \u0026amp; Model Compatibility\"\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\u003eYears\u003c\/th\u003e\n        \u003cth\u003eOEM Part No.\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMariner\u003c\/td\u003e\n        \u003ctd\u003eALL\u003c\/td\u003e\n        \u003ctd\u003e150–300\u003c\/td\u003e\n        \u003ctd\u003e\u003c\/td\u003e\n        \u003ctd\u003e809086\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury\u003c\/td\u003e\n        \u003ctd\u003eALL\u003c\/td\u003e\n        \u003ctd\u003e150–300\u003c\/td\u003e\n        \u003ctd\u003e\u003c\/td\u003e\n        \u003ctd\u003e809086\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eYamaha\u003c\/td\u003e\n        \u003ctd\u003e6 Cyl 3.544 Bore 76 Degree\u003c\/td\u003e\n        \u003ctd\u003e200\u003c\/td\u003e\n        \u003ctd\u003e1998\u003c\/td\u003e\n        \u003ctd\u003e65L-14984-00\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eYamaha\u003c\/td\u003e\n        \u003ctd\u003e6 Cyl 3.544 Bore 76 Degree\u003c\/td\u003e\n        \u003ctd\u003e225\u003c\/td\u003e\n        \u003ctd\u003e1997–1998\u003c\/td\u003e\n        \u003ctd\u003e65L-14984-00\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eYamaha\u003c\/td\u003e\n        \u003ctd\u003e6 Cyl 3.544 Bore 76 Degree\u003c\/td\u003e\n        \u003ctd\u003e250\u003c\/td\u003e\n        \u003ctd\u003e1997–1998\u003c\/td\u003e\n        \u003ctd\u003e65L-14984-00\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eTechnical Specs\u003c\/h2\u003e\n\u003cdl\u003e\n  \u003cdt\u003ePart Type\u003c\/dt\u003e\n  \u003cdd\u003eVST Float Chamber O-Ring Gasket\u003c\/dd\u003e\n  \u003cdt\u003eApplication\u003c\/dt\u003e\n  \u003cdd\u003eVapor Separator Tank (VST) sealing\u003c\/dd\u003e\n  \u003cdt\u003eCompatible Engines\u003c\/dt\u003e\n  \u003cdd\u003eMercury, Mariner, Yamaha 150–300 HP outboards\u003c\/dd\u003e\n  \u003cdt\u003eMaterial\u003c\/dt\u003e\n  \u003cdd\u003eFuel-resistant elastomer\u003c\/dd\u003e\n\u003c\/dl\u003e\n\n\u003ch2\u003eWhat's in the Box\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\u003cstrong\u003e1 x VST O-Ring\u003c\/strong\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eInstallation Notes\u003c\/h2\u003e\n\u003col\u003e\n  \u003cli\u003eDisconnect the battery and relieve fuel system pressure before beginning work.\u003c\/li\u003e\n  \u003cli\u003eRemove the VST cover by loosening the mounting bolts in a cross pattern.\u003c\/li\u003e\n  \u003cli\u003eCarefully remove the old O-ring gasket from the float chamber groove, taking care not to scratch the sealing surfaces.\u003c\/li\u003e\n  \u003cli\u003eClean both mating surfaces thoroughly with a lint-free cloth to remove all fuel residue and debris.\u003c\/li\u003e\n  \u003cli\u003eLightly lubricate the new O-ring with clean engine oil or gasket sealant if specified by your service manual.\u003c\/li\u003e\n  \u003cli\u003ePosition the new O-ring evenly into the float chamber groove, ensuring it seats properly without twisting.\u003c\/li\u003e\n  \u003cli\u003eReinstall the VST cover and torque mounting bolts to manufacturer specifications in a cross pattern.\u003c\/li\u003e\n  \u003cli\u003eReconnect the battery, pressurize the fuel system, and inspect for leaks before starting the engine.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch2\u003eTroubleshooting \u0026amp; FAQ\u003c\/h2\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eHow do I know if my VST gasket needs replacement?\u003c\/summary\u003e\n  \u003cp\u003eCommon signs include fuel odor around the VST, visible fuel weeping from the cover seam, hard starting, rough idle, or loss of fuel pressure. If you're servicing the VST or replacing internal components, always install a new gasket to ensure a proper seal.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eWill this fit my Mercury 200HP EFI outboard?\u003c\/summary\u003e\n  \u003cp\u003eYes, this gasket fits Mercury and Mariner 150–300 HP models that use the VST fuel system. Cross-reference your current part number (809086 or 25-809086) to confirm compatibility.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eCan I reuse the old O-ring if it looks okay?\u003c\/summary\u003e\n  \u003cp\u003eNo. O-rings compress and take a permanent set over time. Reusing an old gasket can result in fuel leaks and inconsistent fuel pressure, leading to performance issues or unsafe conditions.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eWhat's the difference between this and the OEM Yamaha gasket?\u003c\/summary\u003e\n  \u003cp\u003eThis is an aftermarket replacement manufactured to OEM specifications using fuel-resistant materials. It provides equivalent fit and function at a more economical price point.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eDo I need to apply sealant to this O-ring?\u003c\/summary\u003e\n  \u003cp\u003eTypically, no additional sealant is required. A light coating of clean engine oil helps with installation and initial sealing. Always consult your engine's service manual for specific recommendations.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eHow often should this gasket be replaced?\u003c\/summary\u003e\n  \u003cp\u003eReplace the VST O-ring any time the VST cover is removed for service, cleaning, or float adjustment. As a preventive measure, consider replacement every 2–3 years or per your manufacturer's maintenance schedule.\u003c\/p\u003e\n\u003c\/details\u003e\n\n\u003ch2\u003eSafety \u0026amp; Important Info\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003eVerify images\/specifications against your original part. If anything differs—even if your model appears compatible—do not purchase.\u003c\/li\u003e\n  \u003cli\u003eThis is an aftermarket replacement, not an OEM component.\u003c\/li\u003e\n  \u003cli\u003eProfessional installation is recommended for safety and performance.\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"SeaSierra","offers":[{"title":"Default Title","offer_id":51025915347259,"sku":"3509","price":36.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/12_8495a0ba-5801-41de-aa55-fd3fb47be759.jpg?v=1772975126","url":"https:\/\/seasierra.com\/products\/vst-float-chamber-gasket-fits-mercury-mariner-yamaha-150hp-300hp-replaces-65l-14984-00-18-0715-809086","provider":"SeaSierra","version":"1.0","type":"link"}