1995 Johnson/Evinrude Outboards 25, 35 3-Cylinder Service Manual, Page 64Get this manual
3Anti-Siphon Valvesafety standards require permanently installed fuel systems to have anti-siphon protectionThis protection can be afforded in two waysAll 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: PIN 173273 for PIN 173274 for PI 173275 for 5 16