Chrysler 70, 75 and 85 HP Outboard Motors Service Manual OB 3438, Page 28Get this manual
Subsection
_ FUELSySTEM
GENERAL
The fuel system, as defined by this manual, includes all the fuel components common to the system of the motorThese components are the Fuel tankFuel pump, Carburetor and Reed valve Troubleshooting and brief description of the operation of the fuel system are covered in this subsection The reduction of air pressure causes the fuel to be pushed into and mix with the incoming airstream to form combustible air fuel mixtureThe air fuel mixture is admitted to the crankcase of the motor by reed type inlet valves The reed valve operates automatically, opening when the pressure in the crankcase is low enough so the outside pressure can overcome the reed tension Figure 1
OPERATION
The fuel tank is non-pressurized and suction operated diaphragm-displacement type fuel pump on the motor draws fuel from the tank and sends it to the carburetor bowls The upstroke of the piston in the cylinder creates suction which draws air through the throat of the carburetorA restriction in the throat, called venturiacts to reduce air pressure at this point (increasing air velocity