How gas pumps know when to turn themselves off - video

[Frank S]

It’s not the fact that it is 12 volts that is the problem. The design relies on the flow of fuel in the Venturi, creating the suck to make it all work. What you need is a pump of any voltage that delivers the correct flow of fuel through the Venturi. If the pump specs are correct, perhaps the amperage available from your 12 volt source is not enough to run the pump at the desired output.

What IntheGroove, is referring to are the fuel transfer pumps normally mounted on bulk storage tanks either in the bed of a pickup or on a bulk farm fuel tank. Thes pumps are either on or they are off the nozzle does not shut off the pump it merely stops the flow the pump is still running at pressure, but since the valve is closed no fuel comes out. There is no need for those multi valved pressure and flow regulating handles in fact since the pumps are constant pressure constant flow unlike a station pump where the pump is a variable displacement with flow requirements that can go all the way down to near zero flow, these handles do not work very well at all.