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Unread 11-24-2011, 10:06 PM   #16
Castr8r
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The vent line from the roll-over valves goes to the charcoal canister up front, which is vented into the intake. It's a pollution control device that actually works to help your gas mileage, although in a very minor way.

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Unread 11-28-2011, 03:21 PM   #17
mrmud4x4
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Tank Pics

Those caps (2) attach to the single vent line. The vent line is bundled together with the fuel feed and return lines.

I pulled the caps out, they are rollover vents, just like PCV valves, but bigger.

I'm glad I tested them, when I tilted the tank over, the valves worked as they should, but the grommet seals around them seeped by with a little fuel.

I pulled them out, cleaned them up and re-seated them with the black RTV.

It all looks stock to me.
fueltank1-copy.jpg   fueltank1-2-copy.jpg  
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Unread 11-28-2011, 04:04 PM   #18
brentd711
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That vent tube that goes to the can in the engine bay is 1/4" ID and there are two ports on the can, top is 1/4 and lower is 3/8. The vac line off the motor is 1/4, do you connect the vent to the lower fitting with an adapter?
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Unread 11-28-2011, 04:22 PM   #19
mrmud4x4
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Quote:
Originally Posted by brentd711 View Post
That vent tube that goes to the can in the engine bay is 1/4" ID and there are two ports on the can, top is 1/4 and lower is 3/8. The vac line off the motor is 1/4, do you connect the vent to the lower fitting with an adapter?
My vent line (steel tube - 1/8 or 1/4") follows the frame to the front, then ends at the firewall and a hose goes from the steel line to the top of the canister. (just looks like a 1/4" hose) It goes to the smaller nipple on top of the canister right under my window washer bottle. I only see two nipples on top of the canister. I have never messed with it, I installed an MC2100 carb and did the nutter bypass.
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Unread 11-28-2011, 04:38 PM   #20
mrmud4x4
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Quote:
Originally Posted by brentd711 View Post
That vent tube that goes to the can in the engine bay is 1/4" ID and there are two ports on the can, top is 1/4 and lower is 3/8. The vac line off the motor is 1/4, do you connect the vent to the lower fitting with an adapter?
There is also a Cap looking piece that is harder to see, under the washer water bottle, that has two lines going to it that route to the frame and stop, like drain lines. That piece has an upper/lower nipple on it like you describe.

The largest fitting/nipple was routed to my manifold/carb but I disconnected it for my MC2100 swap. That is like 3/8 or 1/2 inch hose, connected to a seperate nipple on top of the canister, next to the fuel vent nipple which is smaller.

So I have Large nipple, small nipple and a cap looking piece with 2 more nipples.

Large nipple - vacuum/manifold
small nipple - fuel vent
cap nipples - drain lines (although these could have been cut and routed down by PO)

Hope this helps out.
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Unread 11-28-2011, 04:39 PM   #21
timatoe
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Quote:
Originally Posted by mrmud4x4 View Post
Those caps (2) attach to the single vent line. The vent line is bundled together with the fuel feed and return lines.

I pulled the caps out, they are rollover vents, just like EGR valves, but bigger.

I'm glad I tested them, when I tilted the tank over, the valves worked as they should, but the grommet seals around them seeped by with a little fuel.

I pulled them out, cleaned them up and re-seated them with the black RTV.

It all looks stock to me.
Ohhhh, see I ran that back to the stock rollover valve up there in the passenger side wheel well. I wonder if it'll pass the pressure test for smog if I just run it up to the canister???
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Unread 11-28-2011, 04:52 PM   #22
mrmud4x4
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Quote:
Originally Posted by timatoe View Post
Ohhhh, see I ran that back to the stock rollover valve up there in the passenger side wheel well. I wonder if it'll pass the pressure test for smog if I just run it up to the canister???
That's one thing I don't have to worry about....I just have a very limited safety inspection here in NC..........lights, horn, wipers.....

I'm pretty sure mine would hold up to a pressure test now.....not sure how that canister is configured on the inside though. (I'm sure there are ways you could get it to pass.....lol...)
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Unread 11-28-2011, 06:35 PM   #23
brentd711
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The can and the tank in my '90 are both from a '93. The can only has two ports, a small one at the top (on the black "cap") and a slightly larger one below it. The smaller one at the top fits my vac line connection but I don't know for sure that's where it goes. I took a quick look through my FSM but didn't see anything about hose routing.
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Unread 11-28-2011, 08:05 PM   #24
pasinbuy
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Quote:
Originally Posted by pasinbuy View Post
Before you install your new plastic tank. Check to see if there is a 6 inch tube in the vent. If the 6 in tube is there cut it to about 1.5 inches to make your plastic tank a true 20 gallon tank.

Other wise it will be a 15 gallon tank.


Quote:
Originally Posted by mrmud4x4 View Post
are you talking about a tube inside the tank?
Sorry I did not get back to you. The vent I am talking about is one of the two large holes on the side of your tank. The smaller of the two. The larger one is your gas fill up.

Look or feel inside, if there is a 6 inch tube. Pull it out and cut it to 1 1/2 inch. This will make your tank a 20 gallon tank.
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Unread 11-29-2011, 05:48 AM   #25
mrmud4x4
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Quote:
Originally Posted by pasinbuy View Post
Sorry I did not get back to you. The vent I am talking about is one of the two large holes on the side of your tank. The smaller of the two. The larger one is your gas fill up.

Look or feel inside, if there is a 6 inch tube. Pull it out and cut it to 1 1/2 inch. This will make your tank a 20 gallon tank.
Won't the other tank top vents still allow you to get 20 gallons in it?

I think, when I pulled my tank, there was a tube inside both the fill and the vent ports. I didn't investigate further, I didn't think they might go down inside the tank.

I can take those hoses off easily.....I will check that out....thanks.
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Unread 11-29-2011, 07:42 AM   #26
pasinbuy
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When the Yj was new there was a 15 gal stock tank. The 20 gallon tank was a option. To save money the mfg place a tube into the vent to make the tank a 15 gal. Then if you choose the 20 gallon option they the placed a 1.5 inch tube into the tank. This way they only had to make one tank.

The 6 inch tube is in the vent only. Not the fill side.
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Unread 11-29-2011, 08:10 AM   #27
doops22
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Quote:
Originally Posted by mrmud4x4 View Post
Those caps (2) attach to the single vent line. The vent line is bundled together with the fuel feed and return lines.

I pulled the caps out, they are rollover vents, just like EGR valves, but bigger.

I'm glad I tested them, when I tilted the tank over, the valves worked as they should, but the grommet seals around them seeped by with a little fuel.

I pulled them out, cleaned them up and re-seated them with the black RTV.

It all looks stock to me.
that's exactly how mine looks. so your saying the white caps act as a rollover valve and don't allow fuel to come up thru the vent and can just route that vent line up with the feed/return?
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Unread 11-29-2011, 08:20 AM   #28
mrmud4x4
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Quote:
Originally Posted by doops22 View Post
that's exactly how mine looks. so your saying the white caps act as a rollover valve and don't allow fuel to come up thru the vent and can just route that vent line up with the feed/return?
yep...mine worked great. I removed the hoses, I tilted the tank, had about 4 or 5 gallons in it, gas seeped around the grommet seal, so I cleaned them up and re-sealed them back into place. Then I re-sealed the cap itself into the grommet.

The vent caps pull right out. The grommet may come out with it.

After you clean the hole edges and grommet....when you are re-inserting the grommet, don't drop it in the tank......

(is that how you spell "grommet"....lol)
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Unread 11-29-2011, 08:30 AM   #29
mrmud4x4
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I don't have any other vent line on the passenger side....I routed to the vent line that goes to the canister up front, on the drivers side.

There is a vent tube with the fill tube, to allow air to escape quickly while filling. Mine was dry rotted, so I replaced that.
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Unread 11-30-2011, 08:19 AM   #30
doops22
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Quote:
Originally Posted by mrmud4x4 View Post
yep...mine worked great. I removed the hoses, I tilted the tank, had about 4 or 5 gallons in it, gas seeped around the grommet seal, so I cleaned them up and re-sealed them back into place. Then I re-sealed the cap itself into the grommet.

The vent caps pull right out. The grommet may come out with it.

After you clean the hole edges and grommet....when you are re-inserting the grommet, don't drop it in the tank......

(is that how you spell "grommet"....lol)
awesome! thanks for the info
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