Reply To: Fuel tank. To vent or not to vent.. that is the question!

[Roger Miller]

What you have there is called a pump-around setup – its two pumps and one pump sends fuel to the carb, and one pump evacuates excess fuel from the carb and sends it back to the tank – with a whole heck of a lot of air.  You must vent the tank, and you may need a bigger vent or two vents to not pressurize the tank.