Chrysler 20 and 30 HP Outboard Motors Service Manual OB 3435, Page 30Get this manual
Subsection
FUELSySTEM
GENERAL
The fuel systemas defined by this manualincludes all the fuel components common to the system of the motor These components are the Fuel tankFuel pumpCarburetor 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 air stream to form combustible air fuel mixture The 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 diaphragmdisplacement type fuel pump on the motor draws fuel from the tank and sends it to the carburetor bowlThe 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