i used these at one time. moved on from them because of this very reason. what i found that sometimes worked for me -key word, sometimes- is:
look down in the carto at the filler. some of mine, when they flooded, the filler was not pushed down in the carto all the way, therefore, it was flooding like crazy.
i used single coils in my tanks so i do not know if duals are different.
i could push the filler down a little and it helped some. don't go crazy with it pushing the filler down too deep. just gently tap it down with a straw. a straw worked perfect for this because it does slides down over the inner tube so you are pushing down only the filler and not tampering with the center tube.
i found this out when i dremeled one apart to get a look at it and try to figure out what the issue was. the filler was not pushed down well. once i gently tapped it down with a straw, it worked a 'little' better.
i moved on from these and found tanks that work perfect for me. however, i did like these, when they worked that is.
good luck to ya