Most carbureted automobile engines utilized mechanical diesel fuel pumps to transfer fuel from the fuel tank into the fuel bowls of the carburetor prior to the widespread adoption of electronic fuel injection. Placing the pump in the tank puts the component least probably to deal with gasoline vapor well (the pump itself) farthest from the engine, submersed in cool liquid. The distance from the pump to the carburetor is comparatively short, so "puller" pumps don't have to work challenging to hold up pressure in the fuel line. This is essential simply because running the vehicle on low fuel will lead to sedimentation of the contaminants (at the bottom of the tank).