Fuel in tank vent line?

[Rian_Colorado]

Hello all

I'm building/installing a charcoal filter for the gas tank vent line, and when I went to inspect the end of the tube - I noticed a small amount of gasoline IN the line (ie, about 1/2 oz dripped out). Am I crazy for thinking that that shouldn't be possible? seems like the vent should be allowing air out, but not liquid?

Wondering if I need a new tank filter?
Thoughts?

Rian

[narly1]

Hello all

I'm building/installing a charcoal filter for the gas tank vent line, and when I went to inspect the end of the tube - I noticed a small amount of gasoline IN the line (ie, about 1/2 oz dripped out). Am I crazy for thinking that that shouldn't be possible? seems like the vent should be allowing air out, but not liquid?

Wondering if I need a new tank filter?
Thoughts?

Rian

The potential for fuel to be in the line to at least to the height of the top of the tank always exists, depending of course on how full the tank is.

Then there is the other case where the tank is full of cool gas which slowly gets warmed up. If the cap is well sealed then the fuel has nowhere to go except up and out the vent.

The solution? Sufficient height and volume in the venting system to accommodate possible fuel expansion or, just avoiding leaving the tank filled all the way.

Earl

[GoDadGo]

Ironically I'm NOT running a charcoal breather and I don't have a gas fume issue.

I intended to install a charcoal canister at the end of the vent line, but in the interim I installed a simple inline plastic fuel filter at the highest point in the vent tubing. Why I don't smell gas fumes doesn't make sense; however, you can see that the plastic fuel filter has some discoloration to it. I put the filter in line to keep stuff from getting into the tank, but left it because it works and works well even though it shouldn't.

Is the filter slowing down the airflow enough that I don't smell fumes or is the vent line so high and so long that that fumes don't make it out of the tank? With that said could you place a fuel filter in between your tank vent outlet and your charcoal canister to solve the problem?

I don't know, but it may be worth a try.

WIX FUEL FILTER #33003

.Good Luck!

[Alphamacaroon]

Doesn't seem that out of place to me. I think if the line is long enough it's very possible for fuel vapor to condense back to liquid in the line— like a passive condenser in a still.

Also I think it makes sense what you are saying GoDadGo— a fuel filter provides nucleation sites (aka surface area) for fuel vapor to condense back into liquid, so it probably does make a fairly effective vapor filter. Keep in mind I'm not a fuel systems expert, but I do know a fair bit about distillation... ;)

[GoDadGo]

Doesn't seem that out of place to me. I think if the line is long enough it's very possible for fuel vapor to condense back to liquid in the line— like a passive condenser in a still.

Also I think it makes sense what you are saying GoDadGo— a fuel filter provides nucleation sites (aka surface area) for fuel vapor to condense back into liquid, so it probably does make a fairly effective vapor filter. Keep in mind I'm not a fuel systems expert, but I do know a fair bit about distillation... ;)

That would explain the discoloration of the plastic body of the fuel filter. Vapors try to escape, end up expanding, then get drawn back into the tank as fuel is consumed. In addition, the vent line runs from the passenger side of the car over to the drivers side so it's darn pretty long and the filter is near the middle.

Your Theory Seems Very Logical & Plausible To Me!