{"product_id":"southmarine-fuel-pump-diaphragm-kit-42990a10-for-mercury-35-275hp-direct-fit-oem-seals","title":"SouthMarine Fuel Pump Diaphragm Kit 42990A10 for Mercury 35–275HP — Direct-Fit OEM Seals","description":"\u003cp\u003e\u003cstrong\u003eSouthMarine Outboard 42990A10 Fuel Pump Diaphragm Kit replaces worn diaphragms and seals in Mercury outboard fuel pumps for engines from 35HP up to 275HP.\u003c\/strong\u003e\u003c\/p\u003e\n\n\u003cp\u003eThis kit is a direct-fit replacement designed to restore proper fuel flow and pressure in a range of Mercury outboards. It contains precision-cut diaphragms and associated sealing components matched to OEM part numbers so you can repair the fuel pump without replacing the entire assembly. The kit is compatible with many numbered fitments and covers a broad spread of horsepower ratings, making it useful for owners, mechanics, and marinas servicing mid- to high-power outboard motors.\u003c\/p\u003e\n\n\u003ch3\u003eWhich Mercury engines and part numbers does this diaphragm kit fit?\u003c\/h3\u003e\n\u003cp\u003eThe kit is built to match multiple OEM references and engine outputs so you can confirm compatibility quickly. It covers a long list of fit part numbers and is suitable across many Mercury horsepower classes commonly found on recreational and commercial boats.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eCompatible fit numbers include 21-42990A1 through A11 and 21-857005A1 variants.\u003c\/li\u003e\n  \u003cli\u003eEngine coverage spans 35HP, 40HP, 45HP, 50HP, 55HP, 60HP, 65HP, 75HP, 80HP, 90HP, 100HP, 115HP, 125HP, 135HP, 150HP, 175HP, 200HP and 275HP.\u003c\/li\u003e\n  \u003cli\u003eCross-references Sierra 18-7817 where applicable for alternative sourcing.\u003c\/li\u003e\n  \u003cli\u003eIf uncertain, supply your engine serial number to verify fitment before purchasing.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhat components are included and how do they restore pump function?\u003c\/h3\u003e\n\u003cp\u003eThe kit replaces the flexible diaphragm and the small seals that control fuel movement inside the pump. Renewing these parts eliminates common causes of leaks, poor priming, and inconsistent fuel delivery, helping the pump regain proper operation.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003ePrecision diaphragms manufactured to match original dimensions and flex characteristics.\u003c\/li\u003e\n  \u003cli\u003eSeals and O-rings for inlet\/outlet ports to prevent fuel or air ingress.\u003c\/li\u003e\n  \u003cli\u003eGaskets or backing plates where required for a secure assembly.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eHow easy is installation for a DIY mechanic?\u003c\/h3\u003e\n\u003cp\u003eInstallation is straightforward for anyone with basic mechanical skills and a few hand tools. Follow a service manual or step-by-step guide, keep the work area clean to avoid contaminating the fuel system, and replace parts one at a time to ensure correct reassembly.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eRemove fuel pump cover and note orientation of parts before disassembly.\u003c\/li\u003e\n  \u003cli\u003eClean mating surfaces and inspect housing for wear or damage.\u003c\/li\u003e\n  \u003cli\u003eInstall new diaphragm and seals, torque fasteners to manufacturer specs.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhen should you choose a diaphragm kit over a full pump replacement?\u003c\/h3\u003e\n\u003cp\u003eChoose the diaphragm kit when the pump housing and drive components are in good condition but fuel delivery issues stem from perished rubber parts. A kit is a cost-effective repair that restores performance without the expense of a complete pump swap.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eUse when leaks, soft primer bulbs, or inconsistent idle are traced to worn diaphragms.\u003c\/li\u003e\n  \u003cli\u003eReplace diaphragms routinely if the engine sees many service hours or old fuel exposure.\u003c\/li\u003e\n  \u003cli\u003eOpt for a full pump replacement if the housing, valves, or drive linkage show corrosion or mechanical failure.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eWho this kit is for: Mechanics, boat owners, and marine service centers who maintain Mercury outboards across a wide horsepower range will find this SouthMarine diaphragm kit a practical repair option. It’s aimed at those who prefer economical, accurate replacements that match OEM fitments and restore reliable fuel pump performance without replacing the entire unit. If you’re unsure about fitment, provide your engine serial number to confirm this kit is the correct match for your outboard.\u003c\/p\u003e\n\u003csection class=\"product-faq-snippet\"\u003e\u003ch3\u003eFAQ\u003c\/h3\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: Is this diaphragm kit compatible with my Mercury engine?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: It covers many Mercury models from 35HP to 275HP; provide your engine serial number to confirm exact fit.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: Can I install the kit myself?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Yes—if you have basic tools and follow the service manual; replace parts in order and seal surfaces cleanly.\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/section\u003e","brand":"SouthMarine","offers":[{"title":"Default Title","offer_id":48084449427614,"sku":"B0BZ3ZB81M","price":34.09,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0781\/2041\/9486\/files\/southmarine-42990a10-front-packaging.jpg?v=1785855728","url":"https:\/\/northtrailauto.ca\/products\/southmarine-fuel-pump-diaphragm-kit-42990a10-for-mercury-35-275hp-direct-fit-oem-seals","provider":"North Trail Auto","version":"1.0","type":"link"}