1969 Evinrude 40 HP Big Twin, Big Twin Electric Lark Service Manual 4596, Page 19Get this manual
DESCRIPTION FUEL FLOW The 40 HP fuel systems consist of fuel tank, fuel pump, and carburetorThe fuel tank is non-pressurized, suction operatedA diaphragm-displacement type fuel pump on the motor draws fuel from the tank and furnishes it to the carburetor through fuel filterCARBURETOR The carburetor is single barrel, float feed typeThe high-speed jet is fixed and only the low-speed needle is adjustableThrottle linkage is synchronized with the magneto by cam on the magneto armature plateINDUCED LOW PRESSURE VENTURI
ATMOSPHERIC AIR PRESSURE