Gas leak

[Walt]

HI all, I built a charcoal canister with aquarium charcoal ,it works fine until I fill up with fuel and then it dumps gas all-over the ground and my feet through the canister,I have tried using a lot smaller inside hose but it still does it, my question is do you think it will work to install a check valve in line between the tank and canister to stop this?

Thanks
Walt

[DaveS53]

A tank vent attached to a charcoal canister should have a fitting that is at the top of the tank. There should also be a roll-over valve located as high as possible, relative to the filler cap, connected with a hose, to the roll-over valve. The canister is then connected from the roll-over valve to any practical location. The hose should have no loops or traps in the routing.

If you have a tank mounted roll-over valve and the filler is significantly higher, then it will run fuel onto the ground, if you have fuel in the fill tube, higher than the valve or the canister. A rollover valve is NOT a check valve, unless the car is upside down, so fuel will run through it, if it's placed too low.

Also, the roll-over valve is usually NOT sized large enough to flow air out of the tank fast enough to permit a normal fast fill of the tank. To accomplish that, you need at least a 3/8" hose routed from the top of the tank to a location just below the fill cap, to allow a lot of air to escape quickly. If you have a problem with fuel burping out and have to fill slowly to prevent it, that's the solution.

http://www.tanksinc.com/index.cfm/page/ptype=results/category_id=160/mode=cat/cat160.htm

[JIMOCO]

Where do you have it mounted? I did the same thing and mounted it as high up as I could on the passenger wheel well. Never had a leak.

[Gumball]

Here is how I have mine mounted - the looped hose connects to the OEM vent bung at the top of the tank. No leakage issues.

http://i845.photobucket.com/albums/ab15/CCRsAC/RearPassengerSideView.jpg (http://s845.photobucket.com/user/CCRsAC/media/RearPassengerSideView.jpg.html)

[Walt]

I have it mounted as high as I could on the passenger side rear wheel well , I also changed to this setup after the car was together.
Walt

[DaveS53]

[QUOTE=Gumball;283169]Here is how I have mine mounted - the looped hose connects to the OEM vent bung at the top of the tank. No leakage issues.

No roll-over valve?

[Walt]

I also will try adding the loops in the line I had it run as high as I could through a bracket on the frame it didn't help.
Walt

[Walt]

Yes there is a OEM rollover valve on the top of the tank behind the fuel pump that is what I have run a hose to the canister.

[Gumball]

Yes there is a OEM rollover valve on the top of the tank behind the fuel pump that is what I have run a hose to the canister.

What he said....

[DaveS53]

Might be wise to read this:

http://www.tanksinc.com/index.cfm/page/ptype=results/category_id=160/mode=cat/cat160.htm

Loops in the line are not wise.

[Gumball]

Might be wise to read this:

http://www.tanksinc.com/index.cfm/page/ptype=results/category_id=160/mode=cat/cat160.htm

Loops in the line are not wise.

Y'know, that is something for me to look at... not sure why I did the loops when installing, it's been quite a few years. I'm wondering now if that had something to do with my low fuel pressure issue recently. If one of those loops filled with fuel, it would make it more difficult to pull fuel out of the tank, as the air wouldn't be freely filling the area that is supposed to be voided by the fuel. Hmmmmmmmm.

[Walt]

I understand the principal they are talking about, question is when the filler is at the highest on the body how do you put the canister higher, and looks like nobody else is having this issue so I'm trying to figure out what's different on mine to cause this issue.
Walt

[edwardb]

I understand the principal they are talking about, question is when the filler is at the highest on the body how do you put the canister higher, and looks like nobody else is having this issue so I'm trying to figure out what's different on mine to cause this issue. Walt

This is where I mounted mine. Exactly the same setup on two Mk4's. Never a wiff of fuel or overflow. I do use the Breeze oversize rollover valve. Not sure it's necessary, but can't hurt. Never had a problem with filling. http://www.breezeautomotive.com/details.php?prod_id=785

http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Update%2005162016/th_IMG_4244_zpscknjh00n.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Update%2005162016/IMG_4244_zpscknjh00n.jpg.html)

[DaveS53]

If you get fuel up into the filler neck, higher that the carbon canister, fuel should come out the top. Apparently the pump shuts off before that happens.
Also looks like you have created a trap at the low spot in the vent hose. The hose should rise steadily upward from the tank to the highest possible point, then down to the canister.

I've got a deck mounted marine filler with only a 1.5 inch hose that's at least 3 feet long. Burping fuel was a major problem, until I added a 3/8" vent hose from the top of the tank, to just below the fill cap. Most people said it would never work unless I increased the filler hose to 2 or 2-1/2". Adding the vent was a lot easier. I knew it had to work on boats, so it should work on my car, too.

[Walt]

I do have my hose run to the top side with holes in the bottom, I'm sure it is higher then the roll over valve on the tank. I thought if I had it hooked in to the bottom side it might get gas in it and not be able to vent.
Walt

[DaveS53]

I understand the principal they are talking about, question is when the filler is at the highest on the body how do you put the canister higher, and looks like nobody else is having this issue so I'm trying to figure out what's different on mine to cause this issue.
Walt

You don't have to put the canister higher, you just have to route a hose to the highest point possible, then down to the canister. The hose routing should have no loops or dips that create a trap. I used a Tanks, Inc. remote roll-over valve and mounted it as high as I could, under the body. The hose from the roll-over valve is routed down to a lower location, where I have the canister located. My canister is inside the car, so another hose is routed outside the body.