ORIGINAL: bigtim
since the muffler is hidden in the cowl of my Hangar-9 P-40 I used a small nylon T fitting,I got it from the local Ace hardware, to make a alternative vent line off the muffler pressure line, when I fill the tank I pull out some of the slack, and pull the plug on the line,placing it in a small cup to catch the fuel.
then when I fill I either hold my finger over the muffler end or I have a little plug that fits the rubber diverter,works great.
the aluminum bracket is drilled so the fuel line slides freely,but the allen head screw wont slip through.
That is the best way.
I also use this set up and works fine, the only difference here is that I attach a spare fuel tank that I carry on my tool box and shut the pump off when fuel is starting to get to the spare tank (I attach the tank to the alternative vent line off the muffler pressure line).