Air leak fuel filter housing

[Dicky]

Just a simple quistion i think i have air leak on the fuel filter housing, i have just ordered new fuel pipe return pipelines 3,5mm normal 3,4mm but does not have so 3,5 would work fine i quess. (internal diameter)
The problem is white smoke and rough starting so i quess after changing fuel filter there is an air leak on the fuel filter housing.
My quistion? is it possible to put on some seal tube on the filterhousing to make it good air tight?....

Putting seal in the filter housing IMO is a massive no, make sure the little turny cap at the front of the housing is tight.