I'm thinking that most needle valves can withstand #5 pressure.
but it depends on the floats displacement as well as the mechanical advantage between the float pivot and the needle in the seat.
Obviously a small float will leak at a lower pressure than if it was bigger.
I find a mechanical fuel pump does the job for a lot of years before needing replacement.
That said, there are valid reasons where someone might find an electric pump
fits the need better than a mechanical system.
But with the little dribble of fuel most lawn/garden engines require, a gravity flow will work just fine, if the tank is above the carburetor
Now there are those that like to have braggin rights saying they have 120 gallons per minute of flow and #15 pressure on their hotrod motor,
that is bored/stroked/ported/polished/balanced yada yada yada.
Well you get the picture.
