I was told when I was looking for field equipment to get a manual fuel pump...because if you loose your battery you can still fly.....years later I still have a manual pump both glow and gas.....
the process of fueling......first thing to remember is a fuel tank is never empty...even if there is no fuel in the tank......ask anyone that has had a pinched vent line.....always remember that as you put fuel in...you must vent air out......Full scale aircraft as well has a tank vent system.
2 line system usually on open cowled airplanes....1 line to carb and 1 line from the muffler......disconnect the line to the carb and fill the tank with that line....... disconnect the the line from the muffler, this is the vent line and over flow when you see fuel from that line the tank is full....
3 line system usually on cowled engines but doesn't have to be......just like the 2 line system except that as your usually under a cowling you cant disconnect lines.....so there is a 3rd line that runs to a fuel dot on the outside of the cowl.....the fuel dot holds the line and also plugs the line(as any open line will cause you to loose tank pressure from the muffler).......the 3rd line runs to the tank as the fill line...I always put a second clunk on my 3rd line so I can defuel the tank to empty...the line to the muffler is still the vent and over flow...when you see fuel coming from the muffler your tank is full......there are fueling valves that replace the 3rd line but I don't recommend them as they can leak and you have to have an adapter for most......hope this helps