THE TANK
The tank of a gravity feed system is always provided with a small hole or vent, usually drilled through the filling cap, through which air may enter to replace the gasoline that is drawn off in the running of the engine. If this hole becomes plugged with dirt, the escape of the gasoline will reduce the pressure in the tank to such an extent that further flow will be prevented, and the engine will stop with all of the symptoms of a lack of gasoline. On opening the tank for the purpose of investigation, the air supply will be renewed, and the engine will again run, to stop slowly as before. Clearing the hole will relieve the condition. This vent may also cause trouble in permitting water to enter and contaminate the gasoline, this being liable to happen when the car is washed.
The pipe by which the gasoline flows from the tank to the carburetor should project slightly above the bottom of the tank, to prevent sediment from being drawn into it.
As gasoline rots rubber rapidly, hose should never be used to conduct it, nor should joints be packed with rubber. Copper and brass are attacked by gasoline less than other metals, and should always be used in preference to iron, which is corroded by the liquid. Joints may be made tight by the use of shellac or soap.