Interesting. I assuming though that this wouldn’t be able to stop the flow of a gas pump wide open? My 38ZR will spit fuel out the vent before clicking the pump off. Wish they had a little more info on this website.

if you are getting fuel spilling out of the vent when fueling then you can do something like this: Fuel Whistle
And i've seen these work pretty good too, but the company that made them has discontinued it..not sure if anyone else makes one... No-Spill tank

Imho
Most boats sit on water ass down. Boats with rear fuel fills will fill harder because iof this. The fuel fills and vents need to be in the air void of the tanks. If liquid is covering /blocking them when trying to fill, these problems happen. Front filling and venting tanks are typically easy to fill, unless boat is tilted forward down for some dumb reason.

For people with rear fill tanks, try unhooking trailer and crank down frt, then try filling. Should be easier unless fuel fill or vent hoses run at some dumb flat or upward at some point.

summary: both the fuel fill and vent connections (along with the rest of the fill hose/vent lines) at tank should be higher than the fuel level itself.

I used to have one of those, worked good. Of course I forgot it at the gas station,,,,.

Mine still spits out even with a front fill and vent, on the water as well.

It has a one-way valve in it, hence the need to mount vertically. Doesn't work perfectly but does keep fuel from streaming out the vent all over the paint LOL Attwood has an inexpensive one that might work about as well, West Marine carries it.

More info on the Lifeguard unit here;

https://www.bakesonline.com/racor-lg...separator.html

The RACOR Lifeguard Marine Fuel / Air Separators meet USCG pleasure craft requirements and allow fuel tank top-off without overboard spillage.

Attwood units http://old.attwoodmarine.com/userfil...-fuel-vent.pdf

Wait until this starts happening when you pee.

Front fill and vent under the fill here. Boat sits level on trailer and not only does the fuel spit out of both the fill and vent but stays in the vent hose which has cause pressure to build in the tank and fuel to push past the fuel pump hat gasket. Seems the whistle above is the only thing that will prevent the vent line for getting filled with fuel as it will alert me the tank is nearly full, unless the Racor LG50 will prevent fuel flow into the vent hose.