Fuel tank vent puking gas !!

[GregWeld]

The other issue is the vent line may be too small -- once some gas gets up inside the vent tube -- the pressure builds up behind it and pushes it out. A LARGER vent tube will allow the pressure to pass the fluid and not push it up and out. Think of a straw....

Hard line has a larger inside diameter... so hard line the same OD would be a better solution than rubber hose... BUT here's my other thought:

DO NOT loop it -- that effectively makes a "P" trap out of the vent line and any "fluid" would sit in the bottom of the "loop" and any pressure behind it would push that fluid up and out of the vent. The fluid in the loop would also block any incoming "make up" air.