1978 Evinrude Outboards 9.9/15HP Service Manual, Page 20Get this manual
FUEL TANK LEAF STOP
The fuel tank is suction operatedFuel is lifted from the tank to the carburetor by the fuel pumpPriming is achieved by squeezing the primer bulb (part of the fuel line) several times or until pressure required to squeeze the bulb increasesThe connector nearest the primer bulb must be connected to the fuel tankSee Figure 3-4
LEAF VALVE
RECIRCULATING VALVESCREEN
LEAF PLATE
Figure 3-2Leaf Valve Assembly LEAF VALVES The leaf valves time the injection of the fuel mixture into the crankcase by opening only when the pressure in the crankcase has dropped to predetermined point on the compression strokeSee Figure 3-2CHOKE The carburetor is fitted with manual choke to reduce the ratio of air to fuel for cold startsA choke valve in the air inlet is mounted to choke shaftWhen the choke knob is pushed in, the valve is held open, allowing air to pass freely through the inletWhen the choke knob is pulled out, the valve is closed, restricting the flow of air to the carburetor See Figure 3-1FUEL PUMP The fuel pump is of the diaphragm-displacement type, and is operated by changes in crankcase pressureAlternate suction and pressure in the crankcase are transmitted to the pump diaphragmFuel is drawn through fine mesh filter before entering the pump, to remove impurities See Figure 3-3PRIMER BULB DRAIN SCREW