1983 Yamaha 30EN Outboards Service Manual, Page 34Get this manual
Connect the short hose to the check valve (outlet), and clamp it with the bandLikewise, connect the long hose to the check valve (inlet), and clamp it with the band FUEL SYSTEM (From bottom cowling to carburetor)
Description: The fuel system (from bottom cowling-to carburetor) consists of the fuel joint (attached to the bottom cowling), fuel filter, and carburetorParticularly, the carburetor has great effect on engine output and, therefore, it must be serviced with special care1Fuel filter The fuel filter removes any water or impurities contained in the fuel to keep them from entering the engineWater collects on the filter cup bottom and impurities are removed by the filter