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AlmostHeavenWV_VW 
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Joined: October 12, 2017
Posts: 1966
Location: WV
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 Posted: Tue Jan 22, 2019 8:04 pm Post subject: Complete Fuel Tank Venting / EVAP System Walk-through |
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| [url=https://www.thesamba.com/vw/forum/viewtopic.php?t=713211] Complete Fuel Tank Venting / EVAP System Walk-through[/url] |
Please forgive the length of this post:
TLDR: There's a lot of info floating around about the EVAP system, but no thorough "Front-to-Back" pictorial/tutorial in any one place. I researched this on the forum to restore my Bug's system. I aim to illustrate this system in it's entirety in one place and include as much info as I can, which I have learned through my readings. I will provide links to the other threads as well, for posterity.
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Most of the pictures are not mine, and some of the descriptions are not mine either. If I added information, I tried to remember to make it bold so that it is differentiated from the original post text.
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---FAQs:
Why should I have this system?
It allows your fuel tank to vent (so your tank will not pressurize itself with changing temperatures (bulge and flex and possible crack and leak). If you restore the system in its entirety, you also will prevent raw fuel vapor from escaping into the atmosphere (i.e. better for the environment AND your car/garage won't smell like gasoline)
Doesn't that EVAP crap kill the performance?
---This system does not affect engine performance.
I don't have an expansion chamber in the trunk, where can I get one?
---Those can typically be found in the Samba classifieds. For supers, a few people have made their own from various materials. https://www.thesamba.com/vw/forum/viewtopic.php?t=301620&highlight=expansion+chamber
Where can I get one of those charcoal canisters?
--- Used from the Samba classifieds, they are not available new. There are two variants, a metal one and a plastic one. The plastic one has a 'pop top' which makes it much easier to refresh.
---Another option is to purchase the 'Mexican Beetle style' charcoal canister. Available from VW of Mexico (Antonio here on the Samba: https://www.thesamba.com/vw/classifieds/detail.php?id=84077 )
How can I refresh the charcoal canister?
---How to refresh/refurbish the charcoal canister: https://www.thesamba.com/vw/forum/viewtopic.php?t=389074
Where can I get the 'pre-made' hard lines for this system?
---They are not available 'pre-made', you must buy a spool of metal line to make them yourself. (Brake/fuel line is commonly used)
Where can I get the hard line clips for the floor pan line and the rear wheel well line?
----Both can typically be found in the Samba classifieds. You could also hunt around at your local hardware store(Ace, TruValu, Lowes, HomeDepot, etc.) too for a suitable line clamp.
Must I use hard metal lines?
---No. In fact, it seems that VW converted to a semi-flexible clear hose at some point, on some models. You could use similar as well if you wish. Probably something like this: https://www.belmetric.com/white-translucent-polyam...du6nvg7ba1
What are the sizes of hose I need?
---Please see sizes listing below
What lengths/how much do I need of the hoses and metal lines?
---You'll have to determine that yourself. It all depends on how you choose to run the lines. A spool of string and a helper will allow you to 'mock up' the lines with the string, then simply measure the string for your lengths. Don't forget to buy a little extra for mistakes!
What is the purpose of this EVAP system?
---This system is designed to transport the raw fuel vapors which are created from the fuel in the tank & contain the vapors in the charcoal canister (located in the right rear wheel well) until the engine is started. The engine fan then blows air into the charcoal canister(where the charcoal then releases the vapors) to then be carried back and into a port on the air cleaner- thereby burning the raw fuel vapors, rather than allowing the vapors to escape into the atmosphere.
When did VW start this system?
---It started in 1968 (IIRC) with a simple hose connected to the tank which was run through a hole in the trunk to underneath the car (much line it does in the full system). However, this line did not have an expansion tank, so it did vent the tank, but on very hot days with a full tank it was common for liquid fuel to burp out of the venting line. Somewhere around 1969, VW added the expansion chamber on the right side of the trunk to alleviate this problem. IIRC this is also when they introduced the entire system- charcoal canister and all as well.
Are supers and non-supers the same?
---All beetles EVAP systems are identical except for their 'expansion canister/fuel trap' which is connected directly to the fuel tank to provide an "auxiliary tank" of sorts to accommodate the expanding liquid fuel on a hot day with a full fuel tank. Supers have theirs in the center of the trunk near the cowl. Standard beetles have their expansion chamber mounted to the right side inside of the trunk.
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---Hose/line sizes: **mm (***approx SAE sizes)
Trunk EVAP hoses (All) = 5mm ID (3/16" is really close)
EVAP metal lines (All) = 5mm OD (3/16" is really close)
EVAP hose 'connectors' between hard lines = 5mm (3/16")
EVAP line engine fan shroud --->charcoal canister = 12mm(1/2")
EVAP line charcoal canister----> air cleaner = 12mm (1/2")
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Let's begin. Starting from inside the trunk:
Here's two pictures to see overall how the EVAP lines run within the trunk
| mnussbau wrote: |
| 74volks wrote: |
| I'm looking for good photos of each & every connection that is made on the fuel system inside the trunk, from the filler neck to the expansion chamber to all connections on the fuel tank itself (top side only). |
I've been looking for the same thing myself so I can restore it to stock. It's difficult as many people don't bother, but I think I've got it right. But I'm not 100% certain. Also, I'm pretty sure there's a mix of fuel and vacuum lines running about...fuel lines on the expansion chamber and gas tank, vacuum lines elsewhere.
****All rubber EVAP hoses in the trunk should be 5mm (3/16")****
I labeled each hose the same on both ends...A runs to A, etc.
Here's the front of the steel expansion chamber.
'A' runs to a 3-way Tee, each end of the Tee is the same size(5mm). 'D' comes out of the top of the canister.
*****Hose "B" (measures 15mm (9/16") I.D.) and Hose "B- elbow" (towards fender) is also 15mm ID****
This shot has a lot of connections...at right you can see where 'B' comes out of the tank, to a Tee under the canister. That Tee is a hard part to find, the "top" of the Tee is large diameter (I think 14mm, whatever that hose is from the tank) while the "vertical" part of the T is vacuum line. I bought a universal-type Tee at Advance Auto, and IIRC I had to add a rubber shim over the fat parts of the Tee to make it fat enough. Then I cranked down on the clamps to make a snug leak-free fit. Something like this...
http://www.partsamerica.com/ProductDetail.aspx?Mfr...Code=4016C
"Tee"
http://www.wolfsburgwest.com/cart/DetailsList.cfm?ID=113201157
Remember 'D' came from the canister, well here it goes to a plastic vent line that runs under the top of the trunk. There are steel bend-tabs that hold that vent line in place. I've never seen a definitive shot of where 'C' should run, so I went fairly high with it to prevent gas from moving through it. It's under the dash area.
Here's the other end of those lines.
Finally, 'C' connects to a nipple on the left side of the gas tank, while 'D' connects to a plastic line that takes a dive under the body, to the right side of the car, then back under the running board to the charcoal canister above the back right wheel. Hope this helps!
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Coming across the cowl and going down in the trunk
Showing the connection of the line coming down from the cowl to the hard metal line which goes underneath the fuel tank
*** No pictures but---There is a rubber hose (5mm) 'connector' between the hardline which makes the transition from trunk to underneath (shown in above picture) to another hardline which is clipped onto and runs diagonally along the front firewall towards the right side of the car (shown in next picture below).****
EVAP line is silver (black line is return line for fuel injection)
EVAP line is silver (black line is return line for fuel injection) This shows the EVAP line 'rounding the corner' with a 5mm rubber hose in the passenger (right side) front wheel well.
"Rounding the corner" 5mm hose in front, passenger wheel well- example #1
"Rounding the corner" in front, passenger wheel well- example #2
****There is typically a rubber hose 'connector' between the front firewall line (above) and the floor pan line (below)****
EVAP line running in 'channel' of right side floor pan. (It jumps front the 'rounding the corner' position through a small cut out in the flange of the pan in OEM style pans to the inner 'channel' (this cut out can be seen in the "Rounding the corner-example #1 picture above). If you have an aftermarket pan, you may not have this cutout- you can choose to make one or simply run the hardline in the outer 'channel'- EVAP line is silver (black line is return line for fuel injection)
(Front corner of right rear wheel well-) 'connector' rubber hose (5mm) at rear end of floor pan hard line from underneath connects here to a hard line which 'arcs' or 'hoops' up around the wheel well, following the fender bolt holes. (This picture appears to have a black vapor line coming up from underneath and into the wheel well.)
Here is a pic of the hardline which 'arcs' in the right rear wheel well. It is unattached in this picture, but the numbers indicate the location of the fender bolt holes. Note the metal bracket hanging on the line in the center of pic. These brackets are bolted up using the fender bolts to hold the line in place (probably only need 3 or 4 to hold the line.) Also can see in this picture how the hardline bends to come up into the wheel well and how the vapor line has a 5mm rubber connector to the small 'stub' on the bottom of the charcoal canister.
12mm hoses from fan shroud (top of can) and back to air cleaner (bottom) shown. There are grommets used by VW where the 12mm hoses go into the engine compartment (not available new- check your local hardware store for grommets or you can use two short pieces of 3/4" rubber hose to act as a grommet of sorts. (the 1/2" hose will slide into the 3/4" hose with a bit of lubrication) Vapor hard line in wheel well and rubber vapor hose (both 5mm) not shown/hooked up here (should go to small 'stub' on bottom of charcoal can next to 12mm stub)
Tech manual pic of the charcoal can hooked up and instruction on which hose goes to which 'stub' (right pic) front expansion chamber (standard beetles) is seen on the left
In this photo, the blue arrows demonstrate where the 12mm hoses to/from the charcoal canister attach (this shows 73 & up 'paper element' airbox, oil bath filter is similar with a 'stub' on the side of the aircleaner)
Here's some overall diagrams of the system:
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Tech manual pics/diagrams showing how the 'expansion chamber' is hooked up and mounted super beetles in the front trunk:
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Diagrams of the entire EVAP system(showing standard beetle expansion chamber, both standard and super beetle systems are identical otherwise) :
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Here's my diagram I made for myself to "see the whole picture" of the EVAP system:
Additional example pictures from gallery:
"Rounding the corner" at front passenger wheel well (also seen is the 'pass through' hole in floor pan)
Line in the body pan clips underneath
Transition from line underneath in floor pan channel into the rear wheel well
Close up view of line in rear wheel well ( Carbon Canister in lower left of this picture)
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APPLEGREENVW
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brotheratkhesahn
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Location: NC
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| Posted: Fri Jan 25, 2019 7:17 pm Post subject: Re: Complete Fuel Tank Venting / EVAP System Walk-through |
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| Thank you so much for putting all of this info in one post. I’ve gotta re-do my lines and charcoal canister, not sure what happened to the originals. |
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AlmostHeavenWV_VW
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Joined: October 12, 2017
Posts: 1966
Location: WV
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| Posted: Sat Jan 26, 2019 7:22 am Post subject: Re: Complete Fuel Tank Venting / EVAP System Walk-through |
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| APPLEGREENVW wrote: |
Wow,nice write up.  |
| brotheratkhesahn wrote: |
| Thank you so much for putting all of this info in one post. I’ve gotta re-do my lines and charcoal canister, not sure what happened to the originals. |
Thanks guys. Glad I could help, it's an oft-talked about, but slightly mysterious system because nobody ever really talked about and demonstrated the entire thing. Took a while to compile it, but I finally got everything together to re-install it in my bug.
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1600DP AK case
Solex 34PICT3 Carb
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Glenn
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| Posted: Sat Jan 26, 2019 7:34 am Post subject: Re: Complete Fuel Tank Venting / EVAP System Walk-through |
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Added to the FAQs / Sticky.
thanks
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
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hopkin
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| Posted: Sat Jan 26, 2019 7:41 am Post subject: Re: Complete Fuel Tank Venting / EVAP System Walk-through |
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Here's a diagram of the Mexican Beetle's fuel system:
Mexican Beetle Expansion Chamber (2 in diagram above):
Charcoal canister (6 in diagram above):
The expansion chamber is mounted in the same place as the older Beetles:
The charcoal canister is mounted under the car, in front of the starter:
If you order the charcoal canister, the right-angle (white) part does not come with it. I don't know if it's available, I used my old one when I replaced mine.
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1971 Super Beetle (past)
1971 Super Beetle (past)
1974 SunBug (past)
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Hoggy81
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| Posted: Mon Sep 02, 2019 4:20 pm Post subject: Re: Complete Fuel Tank Venting / EVAP System Walk-through |
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| While this thread is dealing with the tank venting I don't suppose anyone happens to know what size thread is on the vent connector fitting, it's now discontinued and I need to find a suitable replacement. Thanks in advance. |
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Tim Donahoe
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| Posted: Mon Sep 02, 2019 4:50 pm Post subject: Re: Complete Fuel Tank Venting / EVAP System Walk-through |
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Excellent tutorial!
Tim
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vamram
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| Posted: Mon Sep 02, 2019 5:40 pm Post subject: Re: Complete Fuel Tank Venting / EVAP System Walk-through |
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Yes, AlmostHeaven has put together some of the best how-it-works for things like this. Check out his thread where he builds a home-made and working diagnostic plug tool/computer. Pretty cool.
I like the placing of the charcoal canister under the package tray. I'm thinking of going that route w/my '73.
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outrun1984
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| Posted: Mon Oct 14, 2019 6:16 am Post subject: Re: Complete Fuel Tank Venting / EVAP System Walk-through |
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Very Nice! I am working on a 71 beetle canister project. This was a HUGE help! We are in Vermont so this vehicle has 40 years of oil undercoating could not tell where anything went.
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creative native
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| Posted: Tue Apr 28, 2020 3:44 pm Post subject: Re: Complete Fuel Tank Venting / EVAP System Walk-through |
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| I am so grateful for this wealth of information, AlmostHeavenWV. THANK YOU. |
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Lingwendil
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MuzzcoVW
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| Posted: Thu Oct 22, 2020 7:47 am Post subject: Re: Complete Fuel Tank Venting / EVAP System Walk-through |
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| Thank you for putting all this info together!! It's actually a revelation of sorts. I'm getting ready to restore the system on my F.I. '75...I actually thought the expansion chamber in the trunk was the charcoal canister haha. Now I know my canister is missing, and I have some fab work to do with lines to the rear fender well. Does anyone know where the large line connects from the canister to the intake system on a fuel injected Bug? |
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AlmostHeavenWV_VW
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| Posted: Thu Oct 22, 2020 8:33 am Post subject: Re: Complete Fuel Tank Venting / EVAP System Walk-through |
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From the archives/owners manuals. Looks like it connects to a port on the air cleaner assembly.
Though I can't easily find a photo of the hose port in question, sorry
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Belindance
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| Posted: Fri Apr 23, 2021 1:02 pm Post subject: Re: Complete Fuel Tank Venting / EVAP System Walk-through |
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THANK YOU!!!!! I cannot express enough gratitude for this important information about the mysterious EVAP system. I have a 1970 VW Bug I have owned for almost 40 years. I live in Las Vegas lol, so when living in California this was never an issue.
Years of intense gasoline smell, and filler tank hose failure, with no answer from my hard working local mechanic had a solution. Who knows when the cannister and all it's components were removed from this 1970 VW bug?
Gasoline fumes coming into the attached garage in the summer time, has been very serious problem. This isn't something to just brush off, and ignore.
Since this post, has parts become more easily accessible? My current mechanic believes that you cannot get an old cannister and nobody makes them. Does any of the better known suppliers within the USA, supply a kit? JBugs, Wolfsburg West, West Coast Metric, etc. I know Mexican Bug supplier is mentioned, but anything closer nowadays?
Thank you again, I don't wish what has been my horrible experience with my fuel system and my health decline to be anyone else's experience!!!!! I am truly grateful!! |
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MuzzcoVW
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| Posted: Fri Apr 23, 2021 5:12 pm Post subject: Re: Complete Fuel Tank Venting / EVAP System Walk-through |
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| AlmostHeavenWV_VW wrote: |
From the archives/owners manuals. Looks like it connects to a port on the air cleaner assembly.
Though I can't easily find a photo of the hose port in question, sorry |
thank you! That is the diagram I have been looking for. It's actually not very complicated just a pain when everything has been stripped out. I'll be working on this soon and can't wait to get rid of gas odor when the tank is more than half full. Wouldn't be so bad if gas still smelled like it did in the 70s but it's far different now |
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rmz72
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| Posted: Sun Apr 25, 2021 12:07 pm Post subject: Re: Complete Fuel Tank Venting / EVAP System Walk-through |
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| I have a 1972 Super Beetle and i have been working on making sure the charcoal canister connections are going the correct location. Looking at the diagrams I noticed there should be a line connecting to the fan housing. I looked all over and I cant find a connection for this hose on my fan housing. It appears there should be a connection on the upper right side of the fan housing but no-go on my end. Any ideas? |
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AlmostHeavenWV_VW
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Posts: 1966
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| Posted: Mon Apr 26, 2021 7:54 am Post subject: Re: Complete Fuel Tank Venting / EVAP System Walk-through |
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| rmz72 wrote: |
| I have a 1972 Super Beetle and i have been working on making sure the charcoal canister connections are going the correct location. Looking at the diagrams I noticed there should be a line connecting to the fan housing. I looked all over and I cant find a connection for this hose on my fan housing. It appears there should be a connection on the upper right side of the fan housing but no-go on my end. Any ideas? |
Sounds like you might have an aftermarket fan shroud or have an earlier model year fan shroud.
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1973 Standard Beetle
1600DP AK case
Solex 34PICT3 Carb
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rmz72
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| Posted: Mon Apr 26, 2021 7:33 pm Post subject: Re: Complete Fuel Tank Venting / EVAP System Walk-through |
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| I was thinking it might be an aftermarket. I want to install an oil bath air cleaner so I might have to track down both items in order for the system to work. thanks for the help. |
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DesignBuild
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| Posted: Mon Aug 02, 2021 2:11 am Post subject: Re: Complete Fuel Tank Venting / EVAP System Walk-through |
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The tube fitting in the fan shroud could be a short piece of 1/2 inch galvanized electrical tube MIG welded to the shroud. Put the carb in a plastic bag sealed to the manifold before welding. You don't want to use a fan because it will blow away the gas required for the welding.
The grommets that you could use for the hoses to the canister and from the canister that pass through the right rear wheel well inside panel are the individual headlight wiring grommets used on the Super Beetles. With a bit of liquid soap they should allow a piece of 1/2 inch ID hose to pass through the grommets. If the hoses fit but you want to seal them put some black silicon sealant between the hose and the grommet.
For those of you wondering about the tube and hose lengths look at the pictures in the article. Some have the lengths shown. For those wondering about connecting the canister outlet to fuel injection setups, that is covered in at least one of the pictures here.
Very nicely organized. Some of the hard lines you could use you can find from Inline Tube in Michigan. Try the copper-nickel tube. It is easy to bend and it is strong enough for brake line pipes. It also comes in larger sizes like 1/4 inch and 3/8 inch. There are also some nylon/plastics used now for fuel lines in more modern cars that would be good candidates for the vent tubing along the chassis. Try Summit, Jegs or the outfit that sold the original Moon hubcaps. To bend into a permanent curve you apply heat. You can also get quick connect fittings for much of the plastic fuel compatible tube. The vent tubing in the trunk should meet the SAE specs for gasohol. It is likely the original tubing is not compatible with modern fuels. Some of the clear tubing originally used by VW was vinyl; not compatible with gasoline. There is clear tube that is compatible I just don't know what it is. You can see it on some new lawnmowers or lawn tractors. |
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