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Fuel Tank Vent Valve? |
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CamJam
Moderator Group Joined: Jan/04/2014 Location: Arizona Status: Offline Points: 6547 |
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Posted: Jun/27/2017 at 6:22pm |
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My '72 Javelin (California car) has a small, black plastic canister on the driver's side next to the gas tank. I gather this has something to do with fuel vapor recovery or tank venting. Did all Javelins of this vintage have this, or just California cars? I also have the charcoal canister under the hood.
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'73 Javelin 360 (current project)
'72 Baja Bronze Javelin SST '69 Big Bad Orange AMX (2018 Teague Heritage Award) SOLD |
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304-dude
AMC Addicted Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9082 |
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I think my oem locking gas cap, that was with my 71, is a non vent. Though it has some odd plastic thing that may be a pressure valve.
Here a link to my post, to check your locking gas cap with what is pictured. Mine has an AMC part number that is hidden by the thick rubber seal. I removed it to show in one of the pictures. http://theamcforum.com/forum/oem-locking-gas-cap_topic87884.html?KW=Locking+cap |
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71 Javelin SST body
390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker |
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mmaher94087
AMC Addicted Joined: Apr/01/2008 Location: Arizona Status: Offline Points: 1691 |
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I can't answer your questions as anything '71 and up is a mystery to me. However, the black canister by the tank is a Rollover valve designed to shut off the fuel from the tank. These were first incorporated in the '70 model year.
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Mike
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401MATCOUPE
AMC Addicted Joined: May/20/2010 Location: Salisbury, MD Status: Offline Points: 5367 |
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Cameron....what you are describing is what the Parts Book calls "WCFE"...additionally Mike is correct to. The valve is a roll over valve, it is connected to a plastic tank within your fuel tank....which decreases the amount of fuel you tank holds. Additionally, as Mike has said it was introduced in 1970, carried over 71 up. The WCFE stands for With California Fuel Emissions, which includes the vapor tank in the main fuel tank, roll over valve and tubing that runs from the roll over valve to the rear of the valve cover (1970 only), then in 1971 the Charcoal Canister was introduced which changed the location of the termination point of the line from the tank. Having the engine vacuum (direct) was a really poor way of containing the vapor and was only done for 1 model year. The Tank Venting via Charcoal Canister continued in several ways from 1971 up.
The Gas Cap style (Vented or Non-Vented) had NOTHING to do with the above WCFE system. I edited this post to include info show the split in methods of vapor containment between 1970 and 1971 up cars.
Edited by 401MATCOUPE - Jun/28/2017 at 6:33am |
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Ross K. Peterson
68X,GoPac,343,AT,52A(1stCar) 68X,GoPac,390,4sp,52A 69X,GoPac,390,4sp,64A 70X,GoPac,390,4sp,87A,8 70X,GoPac,390,4sp,BBO,8 70 Jav SST,390,AT,BSO 74MatX,401,AT,Prototype 74MatX,401,AT |
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Mopar_guy
Supporter of TheAMCForum Joined: Jun/07/2009 Location: Ohio Status: Offline Points: 4823 |
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If I may interject, what you're looking at is a liquid separator to keep raw gas from getting to the charcoal canister. This is like a rollover valve but a typical rollover valve is in the top of the tank to keep fuel from going out the vent in case of a rollover.
The TSM describes the liquid separator under the fuel tank vent on the bottom this page, http://www.oldcarmanualproject.com/manuals/AMC/1973/Service%20-%20rescan/image172.html The page before this shows a diagram of the venting system. It also says that expansion tanks were only in 10-40 series cars. Hope this helps. |
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"Hemilina" My 1973, 5.7 Hemi swapped Javelin |
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401MATCOUPE
AMC Addicted Joined: May/20/2010 Location: Salisbury, MD Status: Offline Points: 5367 |
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Mopar_guy....this is a great example of how almost every year AMC changed the "Emissions" systems, to keep up or ahead of Federal Mandates. The WCFE systems as I mentioned before were either not documented or very poorly documented in the TSM's. The Part Catalog is very accurate in the part numbers but can also let you down with poor Illustrations and Diagrams. 1970 is the most confusing since there are actually 3 different part numbers for the Fuel Tank in the Javelin and AMX (Series 30 and 70). I have never found a break in point or Line Number break in, this has caused much confusion over the years for which gas cap to use...Vented or Non-Vented.....wrong cap/tank combination will cause the fuel system to suck the bottom of the tank up and create a vacuum in the tank from fuel being pulled by the fuel pump and no vent to keep it flowing. A great example of the changes to the Charcoal canister is in 1971, the unit had only 2 or 3 nipples (Model and Engine dependent), later canisters had up to 6 nipples for vapor containment.
If you go to that page you quick referenced (thanks), it actually says the Series 10-80 (Matador and Ambassador) are the only models with the Internal Expansion Tank and the "Liquid Check Valve is only on the Series 40 (Gremlin). What it is also saying is that ALL Models had Vented Gas Caps....that actually applies to all Domestic build and sold AMC's from 1971 up. Edited by 401MATCOUPE - Jun/28/2017 at 6:54am |
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Ross K. Peterson
68X,GoPac,343,AT,52A(1stCar) 68X,GoPac,390,4sp,52A 69X,GoPac,390,4sp,64A 70X,GoPac,390,4sp,87A,8 70X,GoPac,390,4sp,BBO,8 70 Jav SST,390,AT,BSO 74MatX,401,AT,Prototype 74MatX,401,AT |
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CamJam
Moderator Group Joined: Jan/04/2014 Location: Arizona Status: Offline Points: 6547 |
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Thanks guys. I've been having some fuel starvation issues and am going to replace the fuel pump today. Want to make sure all the vapor recovery stuff is connected properly while I'm at it. My '69 FSM doesn't cover this, so thanks for the links to the later manual Mopar guy.
I bought a new gas cap recently and thought perhaps I had gotten a non-vented cap, but I see now it actually has a one-way valve to keep the tank from collapsing. There is some evidence that the tank has collapsed slightly, so I assume somewhere in this car's life someone incorrectly installed the wrong cap. Edited by CamJam - Jun/28/2017 at 7:05am |
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'73 Javelin 360 (current project)
'72 Baja Bronze Javelin SST '69 Big Bad Orange AMX (2018 Teague Heritage Award) SOLD |
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CamJam
Moderator Group Joined: Jan/04/2014 Location: Arizona Status: Offline Points: 6547 |
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I think it's a vented cap. The orange plastic piece is likely a one-way valve. If you blow on it it should pass air, but not in the opposite direction. Edited by CamJam - Jun/28/2017 at 11:59am |
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'73 Javelin 360 (current project)
'72 Baja Bronze Javelin SST '69 Big Bad Orange AMX (2018 Teague Heritage Award) SOLD |
||
304-dude
AMC Addicted Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9082 |
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OK, it thought it had a purpose, as it was the first locking cap I ever came across like that from the many cars I had filled. My grandpa had a truck stop and service station. Filled many cars tanks through the summers I was old enough to help. Funny thing way back he declined to pump gas to a diesel car. As he told the owner he did not make much profit on 20 gallon fill ups, and that his tanks were for big rigs that usually go 100 gallons or more a fill. |
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71 Javelin SST body
390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker |
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Mopar_guy
Supporter of TheAMCForum Joined: Jun/07/2009 Location: Ohio Status: Offline Points: 4823 |
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You're welcome. Glad I could help. Yes Ross, the emission requirements were changing every year or so back then. I knew what the valve was since I have one but the TSM pages explained it better than I could. That diagram page is really good. When I move my tank location, I'm actually going to put a charcoal canister back in the car because I'm tired of smelling the fumes.
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"Hemilina" My 1973, 5.7 Hemi swapped Javelin |
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