{"product_id":"mercury-valve-check-21-424811","title":"Mercury – Check Valve Assembly | Fuel System Component | Marine-Grade Construction | 424811","description":"\u003cp data-start=\"0\" data-end=\"97\"\u003e\u003cstrong data-start=\"0\" data-end=\"95\"\u003eMercury – Check Valve Assembly | Fuel System Component | Marine-Grade Construction | 424811\u003c\/strong\u003e\u003c\/p\u003e\n\u003chr data-start=\"99\" data-end=\"102\"\u003e\n\u003ch3 data-start=\"104\" data-end=\"122\"\u003e\u003cstrong data-start=\"108\" data-end=\"120\"\u003eOverview\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp data-start=\"123\" data-end=\"697\"\u003eFuel flow needs to move one way and one way only — that’s where the \u003cstrong data-start=\"191\" data-end=\"237\"\u003eMercury Marine 424811 Check Valve Assembly\u003c\/strong\u003e comes in. Built for \u003cstrong data-start=\"258\" data-end=\"303\"\u003eMercury 150–300HP EFI TwoStroke outboards\u003c\/strong\u003e, this small but essential part keeps your system pressurized and prevents fuel from flowing backward. It’s designed and calibrated by Mercury to hold the exact blowoff pressure your EFI engine needs to run right. Made from marine-tested materials that stand up to heat, vibration, and ethanol-blended fuels, it helps your engine start clean, idle smooth, and stay dependable trip after trip.\u003c\/p\u003e\n\u003chr data-start=\"699\" data-end=\"702\"\u003e\n\u003ch3 data-start=\"704\" data-end=\"726\"\u003e\u003cstrong data-start=\"708\" data-end=\"724\"\u003eKey Features\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli data-start=\"729\" data-end=\"820\"\u003e\n\u003cstrong data-start=\"729\" data-end=\"741\"\u003ePurpose:\u003c\/strong\u003e Stops fuel from flowing backward, keeping the system pressurized and stable.\u003c\/li\u003e\n\u003cli data-start=\"823\" data-end=\"925\"\u003e\n\u003cstrong data-start=\"823\" data-end=\"836\"\u003eMaterial:\u003c\/strong\u003e Constructed from \u003cstrong data-start=\"854\" data-end=\"898\"\u003ecorrosion-resistant, fuel-safe materials\u003c\/strong\u003e designed for marine use.\u003c\/li\u003e\n\u003cli data-start=\"928\" data-end=\"1040\"\u003e\n\u003cstrong data-start=\"928\" data-end=\"944\"\u003ePerformance:\u003c\/strong\u003e Maintains the \u003cstrong data-start=\"959\" data-end=\"987\"\u003efactory blowoff pressure\u003c\/strong\u003e your EFI system requires for consistent operation.\u003c\/li\u003e\n\u003cli data-start=\"1043\" data-end=\"1138\"\u003e\n\u003cstrong data-start=\"1043\" data-end=\"1054\"\u003eDesign:\u003c\/strong\u003e Engineered to \u003cstrong data-start=\"1069\" data-end=\"1094\"\u003eMercury OEM standards\u003c\/strong\u003e for fit, flow, and long-term reliability.\u003c\/li\u003e\n\u003cli data-start=\"1141\" data-end=\"1252\"\u003e\n\u003cstrong data-start=\"1141\" data-end=\"1156\"\u003eDurability:\u003c\/strong\u003e Handles constant vibration, fuel pressure, and high temperatures without leaking or sticking.\u003c\/li\u003e\n\u003cli data-start=\"1255\" data-end=\"1327\"\u003e\n\u003cstrong data-start=\"1255\" data-end=\"1273\"\u003eCompatibility:\u003c\/strong\u003e Fits \u003cstrong data-start=\"1279\" data-end=\"1324\"\u003eMercury 150–300HP EFI TwoStroke outboards\u003c\/strong\u003e.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr data-start=\"1329\" data-end=\"1332\"\u003e\n\u003ch3 data-start=\"1334\" data-end=\"1371\"\u003e\u003cstrong data-start=\"1338\" data-end=\"1369\"\u003eEngine \u0026amp; Boat Compatibility\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli data-start=\"1374\" data-end=\"1470\"\u003e\n\u003cstrong data-start=\"1387\" data-end=\"1467\"\u003eMercury 150HP, 175HP, 200HP, 225HP, 250HP, and 300HP EFI TwoStroke outboards\u003c\/strong\u003e.\u003c\/li\u003e\n\u003cli data-start=\"1473\" data-end=\"1556\"\u003eCommonly found on \u003cstrong data-start=\"1491\" data-end=\"1553\"\u003eoffshore fishing boats, bass boats, and performance setups\u003c\/strong\u003e.\u003c\/li\u003e\n\u003cli data-start=\"1559\" data-end=\"1617\"\u003eSafe for both \u003cstrong data-start=\"1573\" data-end=\"1601\"\u003efreshwater and saltwater\u003c\/strong\u003e environments.\u003c\/li\u003e\n\u003cli data-start=\"1620\" data-end=\"1705\"\u003eDirect replacement for the original check valve assembly — no modifications needed.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr data-start=\"1707\" data-end=\"1710\"\u003e\n\u003ch3 data-start=\"1712\" data-end=\"1755\"\u003e\u003cstrong data-start=\"1716\" data-end=\"1753\"\u003ePerformance \u0026amp; Real-World Benefits\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp data-start=\"1756\" data-end=\"2046\"\u003eA good check valve keeps your fuel system running at the pressure your engine was built for. The \u003cstrong data-start=\"1853\" data-end=\"1869\"\u003e424811 valve\u003c\/strong\u003e prevents backflow, so your fuel injectors stay primed and ready. That means faster starts, smooth throttle response, and steady fuel delivery even after long runs or storage.\u003c\/p\u003e\n\u003cp data-start=\"2048\" data-end=\"2305\"\u003eWhen a valve starts to fail, pressure drops and fuel drains back toward the tank — causing rough starts or uneven performance. Replacing it with this Mercury OEM valve ensures the right pressure balance and reliable fuel flow every time you hit the water.\u003c\/p\u003e\n\u003chr data-start=\"2307\" data-end=\"2310\"\u003e\n\u003ch3 data-start=\"2312\" data-end=\"2344\"\u003e\u003cstrong data-start=\"2316\" data-end=\"2342\"\u003eWhy Choose Mercury OEM\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp data-start=\"2345\" data-end=\"2600\"\u003eThe \u003cstrong data-start=\"2349\" data-end=\"2367\"\u003eMercury 424811\u003c\/strong\u003e isn’t just a part — it’s a pressure-calibrated component made to exact factory standards. Aftermarket valves can look similar, but small differences in internal design or spring tension can throw off your EFI system’s performance.\u003c\/p\u003e\n\u003cp data-start=\"2602\" data-end=\"2841\"\u003eMercury’s OEM check valves are tested for consistent blowoff pressure, fuel resistance, and reliability in harsh marine conditions. It’s a small upgrade that guarantees smoother running and fewer fuel system headaches over the long haul.\u003c\/p\u003e\n\u003chr data-start=\"2843\" data-end=\"2846\"\u003e\n\u003ch3 data-start=\"2848\" data-end=\"2861\"\u003e\u003cstrong data-start=\"2852\" data-end=\"2859\"\u003eFAQ\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp data-start=\"2863\" data-end=\"2958\"\u003e\u003cstrong data-start=\"2863\" data-end=\"2899\"\u003eQ1: What engines use this valve?\u003c\/strong\u003e\u003cbr data-start=\"2899\" data-end=\"2902\"\u003eIt fits \u003cstrong data-start=\"2910\" data-end=\"2955\"\u003eMercury 150–300HP EFI TwoStroke outboards\u003c\/strong\u003e.\u003c\/p\u003e\n\u003cp data-start=\"2960\" data-end=\"3073\"\u003e\u003cstrong data-start=\"2960\" data-end=\"2988\"\u003eQ2: What’s its function?\u003c\/strong\u003e\u003cbr data-start=\"2988\" data-end=\"2991\"\u003eIt maintains pressure and prevents fuel from flowing backward in the EFI system.\u003c\/p\u003e\n\u003cp data-start=\"3075\" data-end=\"3194\"\u003e\u003cstrong data-start=\"3075\" data-end=\"3118\"\u003eQ3: Can it handle ethanol-blended fuel?\u003c\/strong\u003e\u003cbr data-start=\"3118\" data-end=\"3121\"\u003eYes — it’s designed for modern fuel blends and marine-grade durability.\u003c\/p\u003e\n\u003cp data-start=\"3196\" data-end=\"3322\"\u003e\u003cstrong data-start=\"3196\" data-end=\"3236\"\u003eQ4: What happens if the valve fails?\u003c\/strong\u003e\u003cbr data-start=\"3236\" data-end=\"3239\"\u003eYou may notice hard starting, uneven idle, or fuel draining back toward the tank.\u003c\/p\u003e\n\u003cp data-start=\"3324\" data-end=\"3474\"\u003e\u003cstrong data-start=\"3324\" data-end=\"3363\"\u003eQ5: Why OEM instead of aftermarket?\u003c\/strong\u003e\u003cbr data-start=\"3363\" data-end=\"3366\"\u003eOEM valves match your engine’s exact pressure calibration and are built to survive the marine environment.\u003c\/p\u003e","brand":"Mercury","offers":[{"title":"Default Title","offer_id":46941127278883,"sku":"21-424811","price":67.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0783\/7410\/9475\/files\/424811_Main.jpg?v=1760631151","url":"https:\/\/partsvu.com\/en-ca\/products\/mercury-valve-check-21-424811","provider":"PartsVu","version":"1.0","type":"link"}