Chrysler 70, 75 and 85 HP Outboard Motors Service Manual OB 3438, Page 41Get this manual
the main nozzle which mixes downstream with the existing intermediate and idle fuel already flowing in the systemFigure 3 High Speed OperationAs the throttle opening is increased to obtain high speed operation, suction at the main nozzle also increases, lifting greater quantities offuel from the nozzle wellAs this occurs, the fuel level within the nozzle well tends to lowerAs the fuel continues to lower in the fuel wellyou will note that the bottom end of the idle tube will eventually become exposed to incoming carburetor air through the main nozzle air bleed located in the choke boreFigure 2Idle Operation
When this level is reachedthe idle tube is no longer in solid fuel, and the intermediate fuel being delivered through the idle system lessens At this time the throttle would be wide open or near wide open position during maximum or near maximum fuel delivery to the engine High speed fuel then flows from the fuel bowl through the main fuel jet, through the nozzle well area, through the main nozzle and into the engineThe fuel level in the nozzle well is dependent on the fuel being consumed by the engine, and th is in turn dependent upon the throttle opening Figure 4