Venting Gas Tank
xena1
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Has anyone eliminated the charcoal gas fumes filter and vacuum lines? Where is the best place to vent the tank? Thanks!
Venting Gas Tank
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Saddle Tramp
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In the pre-pollution days gas caps use to breathe allowing gas vapors to escape into the atmosphere but I’m not sure you can even buy one anymore. You could just run a line up under the body somewhere (out of harm’s way from dirt and water) with a filter of some sort but be sure to add a rollover valve to prevent the tank from leaking in case of a an fortunate incident.
73CJ
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Took my canister out in 1976. Never had a rollover valve in 73.
I've always run a vented cap. It has a one way valve. Let's air in, but blocks the fuel from running out.
Worked fine with a 1 barrel, 2 barrel and now with Holley FI.
I've always run a vented cap. It has a one way valve. Let's air in, but blocks the fuel from running out.
Worked fine with a 1 barrel, 2 barrel and now with Holley FI.
73jeep
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My 73 had one.
defibvt
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I purchased the liquid check valve from ebay and a roll over valve from delorean. I will use an air breathe to vent from the outlet on the ROV. I looked into purchase a charcoal canister but everywhere wanted to much for them. I will be wheeling this jeep and wanted to prevent and fuel spillage.
stich
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Old thread but a search brought it up. I am putting in a rear tank out of a '76 CJ into my '49 Willys w/Dauntless Buick 225 V6 . The sending unit has two outlets. One for Fuel pump and one for venting? I only have one line running forward to the pump. Should I just run a vent hose up high on the frame with some kind of filter or check valve or just cap it off? Also it has two lines on the left side of tank that were use for the rollover and liquid check valve. Can I just eliminate all this and use a vented cap for ease of install? Right now the two lines on the side are looped to one an other. Help please.
73CJ
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I would vent through the cap and plug the tank sender extra.
The other is for a return line.
The other is for a return line.
Saddle Tramp
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This is the gas tank set up out of the 1977 Tech Manual.
stich
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Thanks SaddleTramp. I found that photo too but don't have/want to use all the "extras" that this system uses. Just want to know what I can safely eliminate and block off to make it work. I guess that a vented cap will work.
jasonmark1993
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Its going to fill your garage with fumes if its inside. I'm actually putting a charcoal canister back on my jeep for that reason.
2008 FJ cruiser sits outside and the 73 CJ is inside
2008 FJ cruiser sits outside and the 73 CJ is inside
Saddle Tramp
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stich
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Its going to fill your garage with fumes if its inside. I'm actually putting a charcoal canister back on my jeep for that reason.
2008 FJ cruiser sits outside and the 73 CJ is inside
Jason, where do you put the canister on at? The extra line coming out of the sending unit or the lines that normally go to the rollover unit? Where would you install the canister? Up high on the frame somewhere?
jasonmark1993
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Some were up under the hood. On my jeep, it was right by the tank up under the drivers rear fender well.
I'm actually going to have to do a little reading on hookup. I've never had to work on one of these systems before.
I think you end up hooking one hose to the tank vent-to the canister-then a hose up to the carb. The engine does have to suck the fumes out of the canister and burn them. Seemed like my original one had a couple extra hoses hanging off it.
I'm actually going to have to do a little reading on hookup. I've never had to work on one of these systems before.
I think you end up hooking one hose to the tank vent-to the canister-then a hose up to the carb. The engine does have to suck the fumes out of the canister and burn them. Seemed like my original one had a couple extra hoses hanging off it.
jasonmark1993
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Yep, no reason not to have one unless you like to smell gas anytime you walk around your jeep.
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I may be wrong, but i believe the "extra" line input/output being referred to is for the fuel return line for vehicles with the filter (by the carb) that has 1 input and 2 output lines. The line will go all the way back to the sending unit to put returned fuel back into the tank.
As far as charcoal canister, mine was under the steering shaft on my rig (a lot newer than your 49 ) and had lines coming from the carb i think... 
actually now that i think of it, i think the lines came from the check valve / roll over valve rear drivers fenderwell area to this, and then a line going out of this TO the air cleaner area (burn the fumes)...
The two lines off the drivers side of the tank went to roll over / liquid check valve.
the filler neck had the main filler tube, and a vent tube that goes to a vented cap.
Thats how mine's all set up.
I only have 1 line coming from the sending unit though like the picture showed. If you have 2, i think the sending unit was for the 2 output filter set-up.
I've heard of people capping it off and doing fine, and also heard of getting vapor lock, and needing it to run.
So not sure there... though you can always get the sending unit replacement with just one line off.
~ Jr
As far as charcoal canister, mine was under the steering shaft on my rig (a lot newer than your 49
) and had lines coming from the carb i think... actually now that i think of it, i think the lines came from the check valve / roll over valve rear drivers fenderwell area to this, and then a line going out of this TO the air cleaner area (burn the fumes)... The two lines off the drivers side of the tank went to roll over / liquid check valve.
the filler neck had the main filler tube, and a vent tube that goes to a vented cap.
Thats how mine's all set up.
I only have 1 line coming from the sending unit though like the picture showed. If you have 2, i think the sending unit was for the 2 output filter set-up.
I've heard of people capping it off and doing fine, and also heard of getting vapor lock, and needing it to run.
So not sure there... though you can always get the sending unit replacement with just one line off.
~ Jr
stich
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Well it looks like I'm on way way to a wrecking yard to try to locate the right canister. I really don't want to smell gas. I've got a fuel cell in the back cargo area now and that's what I put up with now. So if I don't find the complete system. can I get a charcoal canister and use it for fuel venting only? Do you have to have all lines hooked up on the canister for everything to work right?