Fuel Pump: Description and Operation

Fuel Pump:

The mechanical fuel pump mounted to the right front corner of the engine is driven by a pressed steel eccentric cam mounted on the gear end of the camshaft. As the camshaft rotates, the eccentric cam presses down on the pump rocker arm. This action lifts the pull rod and diaphragm upwards against the fuel pump main spring, creating a vacuum in the valve housing and opening the inlet valve. Fuel is drawn into the valve housing chamber. On the return stroke the main spring forces the diaphragm to the down position, which closes the inlet valve and expels the fuel in the valve housing chamber through the outlet valve, to the fuel filter and the carburetor.