{"product_id":"sierra-18-99540-adjustable-spark-tester-for-1-8-cylinder-marine-engines","title":"Sierra Spark Tester 18-99540 with Adjustable Open Spark Gap for 1-8 Cylinder Marine Engines","description":"\u003cp\u003eThe Sierra 18-99540 Spark Tester is a diagnostic tool used to check spark output and ignition performance on marine engines with 1 to 8 cylinders. It features an adjustable section that lets you set an open spark gap, allowing you to visually confirm a strong, consistent spark rather than relying on a plug that may mask a weak or intermittent ignition signal. This makes it a practical first step when troubleshooting no-start conditions, rough running, or suspected ignition component failures on inboard and sterndrive engines.\u003c\/p\u003e\u003cp\u003eThe tester connects in place of a spark plug in the ignition circuit, giving technicians and boat owners a quick visual reference for spark quality across each cylinder. It is compatible with engines ranging from single-cylinder to 8-cylinder configurations, making it a versatile tool for a wide range of marine powerplants. Replacement spark plug wire tips and metric adapters are available separately for use with this tester, extending its compatibility with different wire terminal styles.\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 18-99540\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Name:\u003c\/strong\u003e Spark Tester with Adjustable Section\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCylinder Compatibility:\u003c\/strong\u003e 1-8 cylinder engines\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSpark Gap:\u003c\/strong\u003e Adjustable, open spark gap\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 1.3 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Dimensions:\u003c\/strong\u003e 4.02 x 12.01 x 7.99 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackage Quantity:\u003c\/strong\u003e 1\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 736983855831\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross-Reference:\u003c\/strong\u003e CDI Electronics 519S48\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e1-8 cylinder marine engines\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eCDI Electronics 519S48\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat is the Sierra 18-99540 spark tester used for?\u003c\/strong\u003e It checks spark output and ignition quality on marine engines with 1 to 8 cylinders by letting you view an open spark gap in place of a spark plug, which helps confirm whether the ignition system is firing correctly.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many cylinders does this spark tester support?\u003c\/strong\u003e The Sierra 18-99540 is rated for engines with 1 to 8 cylinders, covering everything from single-cylinder outboards to V-8 inboard and sterndrive engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the spark gap adjustable?\u003c\/strong\u003e Yes, the 18-99540 has an adjustable section that lets you set the open spark gap, so you can vary the test conditions and better judge spark strength and consistency.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-99540 have an equivalent OEM part number?\u003c\/strong\u003e Yes, the Sierra 18-99540 corresponds to CDI Electronics part number 519S48, so either number will identify the same spark tester.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-99540 spark tester weigh?\u003c\/strong\u003e It weighs 1.3 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat are the dimensions of this spark tester?\u003c\/strong\u003e The Sierra 18-99540 spark tester measures 4.02 x 12.01 x 7.99 inches.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I replace the spark plug wire tips on this tester?\u003c\/strong\u003e Yes, replacement spark plug wire tips (P\/N 519-48TA) are available separately for use with the 18-99540 spark tester when the original tips wear out.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eAre metric adapters available for this tool?\u003c\/strong\u003e Yes, metric adapters (P\/N 519-48M) are available separately for the 18-99540 spark tester for use with metric-threaded plug wires.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many spark testers come in the package?\u003c\/strong\u003e The Sierra 18-99540 spark tester ships as a package quantity of one unit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-99540 spark tester?\u003c\/strong\u003e The UPC for this spark tester is 736983855831.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs this spark tester suitable for troubleshooting a no-start condition?\u003c\/strong\u003e Yes, checking spark output with the 18-99540 is a common first diagnostic step for no-start or rough-running conditions, since it lets you see whether each cylinder is producing a strong spark.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988446032091,"sku":"SIE-18-99540","price":230.78,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/CDI-519-S48_lg__76580.1558113106.500.750.jpg?v=1785189209","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-99540-adjustable-spark-tester-for-1-8-cylinder-marine-engines","provider":"Good Vibes Marina","version":"1.0","type":"link"}