1999 "EE" Evinrude 200, 225 V6 FFI Outboards Service Manual, P/N 787025, Page 112Get this manual
3Antisiphon Valvesafety standards require permanently installed fuel systems to have antisiphon 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 antisiphon valve installedAntisiphon 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:
PI 173275 for PI 173273 for PI 173274 for
in0.0copper in1.0hose 3B in1.0hose
4Fuel Distribution Linesminimum inside diameter of 3B in(9,5 mm) is required for V6 and larger outboards3B 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 "81"Vinyl hose must not be used in permanently installed fuel distribution system5: