{"product_id":"marine-fuel-filter-for-gm-ford-v-8-up-to-400-hp-mercruiser-224-cid-replaces-35-53336-sierra-18-7721","title":"Sierra 18-7721 Fuel Filter, Replaces 35-864572, for MPI \u0026 EFI Engines with Boost Pump, 8.1L \u0026 496 CID","description":"\u003cp\u003eThe Sierra 18-7721 is a replacement fuel filter engineered for MPI and EFI marine engines equipped with a boost pump, specifically 8.1L and 496 cid applications running 3\/8 inch ID fuel lines. It is a direct equivalent for the OEM Mercury Marine 35-864572 filter, giving boat owners a straightforward way to restore proper fuel filtration without sourcing the part through the engine manufacturer.\u003c\/p\u003e\u003cp\u003eThe filter uses a metal outer housing sized at 0.38 inches in diameter and is built to trap contaminants at a 180 micron rating, protecting the fuel injection system and boost pump from debris that can cause clogging, poor performance, or injector wear. Because it is purpose-built for MPI and EFI engines with a boost pump, it is not intended for carbureted fuel systems, which use a different Sierra filter in this catalog family.\u003c\/p\u003e\u003cp\u003eRoutine replacement of the fuel filter is a standard part of marine engine maintenance, and using a properly rated filter like the 18-7721 helps maintain consistent fuel pressure and delivery. The part is identified by the Sierra part number 18-7721 and is cross-referenced to the OEM Mercury Marine number for buyers who are matching by OEM part number.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-7721\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Fuel Filter\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReplaces (OEM):\u003c\/strong\u003e 35-864572\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFitment:\u003c\/strong\u003e MPI and EFI engines with boost pump, 8.1L and 496 CID, for 3\/8 inch ID fuel lines\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMicron Rating:\u003c\/strong\u003e 180\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOuter Material:\u003c\/strong\u003e Metal\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eItem Diameter:\u003c\/strong\u003e 0.38 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.32 pounds\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMPI and EFI engines with boost pump\u003c\/li\u003e\n\u003cli\u003e8.1L and 496 cid engines\u003c\/li\u003e\n\u003cli\u003eFor 3\/8 inch ID fuel lines\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e35-864572\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part number does the Sierra 18-7721 fuel filter replace?\u003c\/strong\u003e The Sierra 18-7721 fuel filter replaces Mercury Marine OEM part number 35-864572.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat engines is the 18-7721 fuel filter designed for?\u003c\/strong\u003e It is designed for MPI and EFI marine engines equipped with a boost pump, specifically 8.1L and 496 cid applications.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat fuel line size does the 18-7721 fit?\u003c\/strong\u003e This filter is built for 3\/8 inch ID fuel lines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the micron rating of the Sierra 18-7721 fuel filter?\u003c\/strong\u003e The 18-7721 has a 180 micron filtration rating.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material is the Sierra 18-7721 fuel filter housing made of?\u003c\/strong\u003e The outer housing of the 18-7721 fuel filter is metal.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-7721 fuel filter weigh?\u003c\/strong\u003e The 18-7721 weighs 0.32 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the diameter of the Sierra 18-7721 fuel filter?\u003c\/strong\u003e The 18-7721 has an item diameter of 0.38 inches.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill the 18-7721 work on a carbureted engine?\u003c\/strong\u003e No, the Sierra 18-7721 is built specifically for MPI and EFI engines with a boost pump, not carbureted fuel systems.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-7721 a genuine Sierra part?\u003c\/strong\u003e Yes, 18-7721 is the Sierra part number for this fuel filter, sold as a Sierra-branded replacement for the Mercury Marine 35-864572.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-7721 fuel filter a universal fit?\u003c\/strong\u003e It fits any MPI or EFI engine with a boost pump that uses 8.1L or 496 cid displacement and 3\/8 inch ID fuel lines, rather than being limited to a single boat make or model.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I know if the 18-7721 is the correct fuel filter for my engine?\u003c\/strong\u003e Confirm your engine is an MPI or EFI type with a boost pump in the 8.1L or 496 cid range using 3\/8 inch ID fuel lines, or match against OEM number 35-864572, before ordering the Sierra 18-7721.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988387049691,"sku":"SIE-18-7721","price":42.05,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-7721_lg__06951.1558131853.500.750.jpg?v=1785188286","url":"https:\/\/www.goodvibesmarina.com\/products\/marine-fuel-filter-for-gm-ford-v-8-up-to-400-hp-mercruiser-224-cid-replaces-35-53336-sierra-18-7721","provider":"Good Vibes Marina","version":"1.0","type":"link"}