By installing a filter (with the element removed) you are effectively adding an expansion chamber to your back-pressure line, which will subsequently reduce the pressure of the air travelling through the fuel line. Try this analogy: if you pass air at an equal velocity through both a drinking straw (representing your back pressure line) and then a cardboard cylinder, (representing the fuel filter) the pressure of the air that exits the straw should be greater.
By reducing the pressure of the air that exits your back-pressure line, you should reduce this 'foaming' effect.
I'm not trying initiate an argument...just trying to help you out
Also, make sure that you loose mount your fuel tank.