with use mechanical fuel pumps. It only when the tanks are located far from the engine or below the mechanical lift pumps specifications for feet of lift that there is an electric pump installed. Plenty of owners install them for various reasons. Chiefly being involved with priming the filters and bleeding the engine. Mine has a valve so that I can prime the filters or change the direction of the pump to fill the day tank to my diesel heater. Some have pumps to pump from the tank into a container so that they can fill their filters manually. Some put them in so that if the mechanical pump fails they can switch on the electric pump as a back up to feed the injector pump. An electric pump in the system makes so much sense that it's a wonder that every boat doesn't have one. My main engine doesn't need one and didn't have one installed when I bought the boat but my generator is installed higher then the main and needs one of it's own because it's lift pump isn't strong enough.