{"product_id":"sierra-18-99408-trigger-for-mercury-mariner-4-cyl-outboards-1988-1997-replaces-99021a2-fits-80-jet-100-115-125-hp","title":"Sierra Trigger 18-99408 for Mercury\/Mariner 4 Cylinder Outboards 1988-1997, Replaces 99021A2, 99021A6, 99021K2","description":"\u003cp\u003eThe Sierra Trigger 18-99408 is an ignition trigger built to restore reliable spark timing on Mercury and Mariner 4 cylinder outboard engines. The trigger is a core ignition component that signals the engine's control module to fire the spark at the correct point in the crankshaft rotation, and a worn or failing trigger commonly causes hard starting, misfiring, rough idle, or a no-spark condition. Replacing the trigger with the Sierra 18-99408 restores the factory ignition signal path without needing to source a used or salvage part.\u003c\/p\u003e\u003cp\u003eThis trigger is designed to fit Mercury\/Mariner 4 cylinder engines built between 1988 and 1997, covering the 80 JET, 100, 115, and 125 HP models. It is a direct cross to the OEM Mercury numbers 99021A2, 99021A6, and 99021K2, so it installs in place of the original trigger using the factory mounting points and wiring connections.\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 18-99408\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Ignition Trigger\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFits:\u003c\/strong\u003e Mercury\/Mariner 4 Cylinder Outboards\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHorsepower Coverage:\u003c\/strong\u003e 80 JET, 100, 115, 125 HP\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eModel Years:\u003c\/strong\u003e 1988-1997\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.6 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282394394\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMercury\/Mariner 4 cylinder outboards, 1988-1997\u003c\/li\u003e\n\u003cli\u003e80 JET, 100, 115 and 125 HP\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e99021A2\u003c\/li\u003e\n\u003cli\u003e99021A6\u003c\/li\u003e\n\u003cli\u003e99021K2\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-99408 trigger fit?\u003c\/strong\u003e The Sierra 18-99408 fits Mercury\/Mariner 4 cylinder outboard engines built from 1988 to 1997, specifically the 80 JET, 100, 115, and 125 HP models.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhich OEM Mercury part numbers does this trigger replace?\u003c\/strong\u003e The Sierra 18-99408 replaces Mercury OEM numbers 99021A2, 99021A6, and 99021K2.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-99408 trigger weigh?\u003c\/strong\u003e It weighs 0.6 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill this trigger fit a 6 cylinder Mercury outboard?\u003c\/strong\u003e No, the Sierra 18-99408 is designed specifically for Mercury\/Mariner 4 cylinder outboards, not 6 cylinder models.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat symptoms indicate the trigger needs to be replaced?\u003c\/strong\u003e Hard starting, misfiring, a rough idle, or a complete loss of spark on a Mercury\/Mariner 4 cylinder outboard can indicate the trigger, such as the Sierra 18-99408, has failed.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-99408 a genuine Mercury part or aftermarket?\u003c\/strong\u003e The 18-99408 is an aftermarket trigger manufactured by Sierra, built to replace the OEM Mercury 99021A2, 99021A6, and 99021K2 triggers.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 125 HP Mercury outboard use this trigger?\u003c\/strong\u003e Yes, the 125 HP Mercury\/Mariner 4 cylinder outboard (1988-1997) is covered by the Sierra 18-99408 trigger.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat years of Mercury\/Mariner outboards use the 18-99408 trigger?\u003c\/strong\u003e Model years 1988 through 1997 for the applicable 4 cylinder Mercury\/Mariner outboards use this trigger.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 80 JET model use the same trigger as the 100 HP model?\u003c\/strong\u003e Yes, the Sierra 18-99408 covers both the 80 JET and the 100 HP Mercury\/Mariner 4 cylinder outboards, along with the 115 and 125 HP models.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-99408 trigger?\u003c\/strong\u003e The UPC for the Sierra 18-99408 Mercury\/Mariner trigger is 808282394394.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988442853595,"sku":"SIE-18-99408","price":123.28,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/CDI-134-9021-4_lg__23559.1748371108.500.750.jpg?v=1785188669","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-99408-trigger-for-mercury-mariner-4-cyl-outboards-1988-1997-replaces-99021a2-fits-80-jet-100-115-125-hp","provider":"Good Vibes Marina","version":"1.0","type":"link"}