Unfortunately, not all transfer pumps are self-priming, so you should know about the start-up if you decide on a manual one. Priming the pump is necessary to increase the pressure that exerts the liquid out of the pump. First, however, you need to close the fuel line supply entirely and press the pump in an up and down motion to create high pressure. After you are done with this, you can close the fuel line, remove the pump and use it!