Gas Tank Venting

[Mechie3]

I want to delete the purge solenoid off the car, since i likely won't have the charcoal canister in place anyways, so it won't do anything.

What does FFR typically do for the roadsters? Subaru's sometimes have problems filling the gas tank if the charcoal canister is plugged and can't vent.

[longislandwrx]

I don't think it's an issue, The short wide fill tube should be wide enough to let plenty of air by. Its also a straight shot in unlike the oem tank that has that plastic elbow baffle

[VD2021]

If you go this route expect your fuel fill-up time to be slow and for your garage to, almost always, smell of gas fumes. This will increase along with the garage temperature?

[longislandwrx]

I have a 68 firebird with a vented cap, fumes are never too bad, even on hot days. It won't be squeaky clean but I think its tolerable. Maybe a much smaller charcoal can would be beneficial. The one on my rx7 wasn't too large. I certainly wouldn't use the wrx's cinderblock sized can.

[Tony Zullo]

Hi guys i just did a charcoal canister in Nates 33 hot rod ....ran from vent to canister worked great with fill and smell...Tony@ffr

[Mechie3]

Any details? I'd be interestedin something like that.

[VD2021]

Here are a few options.

http://www.ffcars.com/forums/17-factory-five-roadsters/233422-charcoal-filter.html#post2091225
http://www.ffcars.com/forums/17-factory-five-roadsters/170238-my-take-fuel-vapor-canister.html
http://thefactoryfiveforum.com/showthread.php?506-More-progress-made-on-the-body-%29&p=46380&viewfull=1#post46380

[wallace18]

I got a canister from a Mazda in a you pull it junk yard for $5.00. Nice and small. Get the mounting bracket as well. I hooked it up to my Boyd tank for my 33 and works great. An open line will smell up the garage. Trust me I know.

[Tony Zullo]

Just use a GM canister single in and out,,got it off Amazon about $40.

[Xusia]

Thanks Tony. I did several searches on Amazon and came up empty. Do you have a more specific product name, or perhaps a link?

[Tony Zullo]

ACDelco 215-75 Canister Assembly..Thats the # on Amazon..

[Xusia]

Awesome! Found it, thanks!

[svanlare]

This is an old thread, but hope nobody minds me hijacking. Seems better than starting a new thread since it is the same topic.

I'm thinking of adding a smaller canister and keeping the purge valve so that I have no gas fumes in the garage. After reading up, it seems pretty easy to keep the system mostly closed. Here is what I'm thinking for my '07 donor, please let me know if I have any of this wrong or should be thinking differently about this, as a few days ago I would have been hard pressed to spell EVAP, much less design mod the system on my car.

To start with, this is the stock EVAP system for my Subaru. Given the OEM tank is gone and the replacement has only fuel pump, fuel level, vent and fill as openings, things like the temperature sensor and fuel cutoff just don't exist anymore. I assume that whatever I do, there will be some programming to turn off the check-engine-light. I read a nice article at www.diycardoctor.com (http://www.diycardoctor.com/automotive_evap_system.htm) that got me started on thinking 80's and 90's level EVAP control would be pretty simple to implement and I wouldn't have to worry about smelling up the garage or replacing the filter.

http://i.imgur.com/gwvIDhx.jpg (http://imgur.com/gwvIDhx)

The first option I think is the way that is recommended in the build instructions. Cut out everything related to EVAP, vent the tank to the atmosphere, and cap the lines going to the turbo and throttle body. That leaves me with the following schematic and I think where this thread started. There will be some codes to ignore in the ECU, but the only downside seems to be the risk that the car will smell of gas fumes occasionally. On the plus side, this is as light and simple as you can go.

http://i.imgur.com/d9jV6SX.jpg (http://imgur.com/d9jV6SX)

The next step seems to be adding a charcoal canister or air filter and stopping there. If I understand how that works, the charcoal will absorb odors but eventually the canister will saturate and will have to be replaced. I've also read on a number of blogs where a small K&N type filter is used and put on a stalk. Simple but it seems to make the filter a replacement item.

http://i.imgur.com/WXd3U8I.jpg (http://imgur.com/WXd3U8I)

I'm thinking about going one step further and adding the purge line and solenoids back into the system. Then the system appears as shown below. Given the system operates via vacuum to pull purge air through the canister, the fact that the pressure control valve is missing I don't anticipate to cause any issues. I think that valve is just used to pressure test the system as opposed to when the purge is happening.

http://i.imgur.com/z39UFrk.jpg (http://imgur.com/z39UFrk)

As for filters, The AC Delco 21575 and Miata are both mentioned as good candidates on various blogs. The GM part is around $50 new at amazon and was used in a huge number of cars from the cimaron to the corvette and from the mid 80's to the late 90's. The Miata part is smaller, but $100 new. It has a nice bracket though vs. just a banjo strap and picked up on eBay both are probably cheaper than the new GM part. Even though I race a Miata, I don't have a manual page for the EVAP system, but I did find this one for the GM. Pretty simple.

http://i.imgur.com/Rw9axbb.jpg (http://imgur.com/Rw9axbb)

The only other twist I have in the option 3 schematic, is having a vent line to making filling easier. Not my contribution, blatantly lifted from this thread.
How-can-you-tell-when-the-fuel-tank-is-full (http://thefactoryfiveforum.com/showthread.php?17808-How-can-you-tell-when-the-fuel-tank-is-full)

I welcome any and all comments and thoughts, especially before I start doing the work this weekend :-)

[Hindsight]

Tough to say if you actually need the purge. As fuel is removed from the tank via fuel injection, air will be drawn in to the tank and that air will help purge the charcoal can. Reading on roadster and other hot rod forums, it seems a number of guys run a charcoal can with no purge and they never have issues with the can saturating/clogging.

I made my own can from pvc and aquarium charcoal. Zero gas smell in garage. I have pics of it along with detailed pics of the fuel tank fill vent discussed in the link you posted.

[Pearldrummer7]

I have an open line that routes tight to the firewall then goes out the bottom of the passenger area. Stick under the body about 1/16". Doesn't smell unless you get right under the body and doesn't seem to cause any other issues. It's definitely not the most elegant solution, but it's a cheap one.

[tmoretta]

The gas smell from my 818 is from the slight seepage where the fuel pump mounts to the original FFR tank. Is there any kind of improved o-ring or other fix to solve this common problem? I have to remove my seats and firewall to make a fix, so I would like to do it just one more time.

[Pearldrummer7]

The gas smell from my 818 is from the slight seepage where the fuel pump mounts to the original FFR tank. Is there any kind of improved o-ring or other fix to solve this common problem? I have to remove my seats and firewall to make a fix, so I would like to do it just one more time.

Black silicone seems to work for me (link (http://www.harborfreight.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/i/m/image_15228.jpg))

[Hindsight]

I think silicone can break down over time when exposed to fuels. Might not be a problem on the tank gasket at the top of the tank, depending on how much fuel sloshes on it over time. I would suggest Nitrile. Something like this: http://www.summitracing.com/parts/mrg-77b?seid=srese1&gclid=CjwKEAjwkK6wBRCcoK_tiOT-zFASJAC7RArizA5cziVZRsQ62XPiAV2LdxTdawqPnf6g-664izTpRRoC_tvw_wcB

[Pearldrummer7]

I was told the black silicone is fuel resistant. Now that I type that, that could mean it just slowly breaks down.

Regular silicone breaks down immediately, and this doesn't, though.

[TouchStone]

Tough to say if you actually need the purge. As fuel is removed from the tank via fuel injection, air will be drawn in to the tank and that air will help purge the charcoal can. Reading on roadster and other hot rod forums, it seems a number of guys run a charcoal can with no purge and they never have issues with the can saturating/clogging.

This is what I am doing with the GM canister. Also put a tiny air filter at the end of the vent line. I had zero gas smell in my garage this summer, in Texas.

[Jim Haar]

I made my own can from pvc and aquarium charcoal on my Cobra build. Zero gas smell in garage.
Simple enuf.........

[Frank818]

I am re-using my old VW charcoal canister, which is much smaller than Subaru's and much easier to connect.

[DMC7492]

I went for simplicity on the complete venting system. Custom made charcoal can and -6 braided hose. Mounted It next to the tank serves as a rollover vent at the same time.
50590
50591
50597

[redfogo]

I have ran cars with no charcoal can and honestly have never had any smell issues.

[Jamespbaum]

I spent a bunch of time thinking about how to vent the new tank with my 2007 donor setup. The instruction manual from FF was not very useful so I wrote up what I learned and did. Hopefully this can help somebody else who's seeing that the manual's venting instructions don't make sense and wondering what to do.

https://www.dropbox.com/s/5udu7r5576iu8qe/2007WRXFuelPumpandFactoryFiveNewFuelTankInstallati onConsiderations.pdf?dl=0

[ben1272]

Hi James, nice write up.

Doesnt FFR show cutting one of the tubes very short for converting it into a vent? I have manual rev 1o, pages 62-63

[Jamespbaum]

You mean I could have just read the manual and saved a bunch of time?? :) :)

I must have an older version or I just blew by it. Not the first time, nor the last, I'm sure. At least it forced me to learn the theory of the jet pump and fuel sending circuit.

[tmoretta]

After completely filling my fuel tank, I think my Miata charcoal canister has become saturated, as there is now strong gas smell. Should I somehow purge the canister, is it ruined, or will it evaporate the fuel on its own? And, if I want to purge the canister, which of the 3 ports would I connect and to where? Intake manifold?

[Loring]

It just occurred to me that because I'm still utilizing the jet pump that I won't have a vent line. Perhaps I'll have to use the fuel feed as a vent line rather than capping it. Current plans for feed line are 1/2" bulkhead fitting.