1990 Johnson Evinrude 120 thru 140, 185 thru 225, 300 HP, P/N 507875, Page 78Get this manual
3Anti-Siphon Valvesafety standards require permanently installed fuel systems to have anti-siphon protectionThis protection can be afforded in two ways: All fuel distribution lines must be secured above the highest fuel level when the boat is in its normal, unloaded, static floating position Each fuel pickup tube must have an anti -siphon valve installedAnti-siphon valves used must have pressure drop of no more than 2.5 inof mercury (Hg) at flow rate of 20 gallons per hourThe following OMC valves meet this requirement: PI 173273 for PI 173274 for PI 173275 for 16 5 3 3
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4Fuel Distribution Linesminimum inside diameter of 3fs in(9,5 mm) is required for V6 and larger engines38 in(9,5 mm) is preferred for V4 and smaller engines, while minimum of 5A6 in(7,9 mm) is requiredDistribution lines must be USCG Type "A" reinforced neopreneVinyl hose must not be used in permanently installed fuel distribution system5Fuel Distribution Fittingsall fittings must have an inside diameter of: