Originally Posted by sailah
I took apart the fuel cap and you are correct it only vents one way. Why?
Letting fuel fumes out is probably prohibited by emissions regs, except via a charcoal canister. That's just a guess, though.
I disabled the one way venting system so now it vents both ways and it pulls air around the fuel filler "moat" Hopefully that will allow the main tank to vent enough so that it's not forcing it up subtank vent. Now the question is how to make the subtank vent so that water can't get in from rain.
I think I can form a wall with some JB weld and shove some gas foam down there to keep most of the water at bay.
Another option would be to run the vent line into the main tank through the fuel filler cap. Any spew would just go into the tank. Routing the vent line to the front of the tank would prevent length problems when the filler cap hinged forward to open.
Or, you could [edit:never mind, you'd just dump fuel with this idea.]
There might be problems with both suggestions, but they might also be helpful.