1999 "EE" 90, 115 FFI, 150, 175 V4, V6 FFI Outboards Service Manual, P/N 787024, Page 116Get 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 inHg at flow rate of 20 gallons per hourThe following OMC valves meet this requirement:
173275 for PI 173273 for PI 173274 for
in0.0copper in1.0hose in1.0hose
4Fuel Distribution Linesminimum inside diameter of 38 in(9,5 mm) is required for V6 and larger outboards38 in(9,5 mm) is preferred for V4 and smaller outboards, while minimum of 516 in (7,9 mm) is requiredDistribution lines must be USCG Type "A1" or "B1"Vinyl hose must not be used in permanently installed fuel distribution system5Fuel Distribution Fittingsall fittings must have an inside diameter of: 2-Cyl 3-Cyl V4, and V6in(6,4 mm) minimum, 9132 in(7,1 mm) preferred 6Fuel Filterfuel filters must have pressure drop of no more than 0.4 inHg at flow rate of 20 gallons per hourThe filter should have minimum filtered area of 200 sqin(1290 cm )