LRA aux tank and slight gas smell

[mep1811]

I had a gas smell during the summer during a long trip. One issue was the vent filter was clogged with dust. Not much of an issue but with a lot of off road driving it fills up with dust.

The other issue was I getting Trac Off , 4Lo and Check engine warning lights. This combination of lights indicate a charcoal canister failure.
Since I was on the road and was heading to Montana I called @OverLand Cruisers ,explained my issue and set up an appointment to have this checked out as well as a service. Kudos to @OverLand Cruisers to setting aside time for me while passing through while on the road.

The lights were easily cleared through my Scan Gauge.

The vent filter was cleaned and we talked about if there was a way to relocate the filter so it could be serviced in the field. Something for the future.
A check of the charcoal canister revealed a short that was causing the internal fan to keep running. Since the canister was under warranty, I choose to deal with that when I got back to El Paso. ( It was replaced under warranty)

Before my next extended off road trip, I'll get the tank vent relocated so it can be field serviceable.

Hope this help someone.

 

[clearmysix]

What about just not putting gas in the Aux tank until fixed so you don’t have to worry about fuel smell.

Unfortunately it’s a connected system so it doesn’t matter where the fuel is the vapor smell remains.

 

[Markuson]

What’s the maintenance on these LRA tanks?

I have one of the earliest 24’s here and I’ve never done anything to it but add gas. Lots and lots of gas…

 

[WCDAVE]

Do you have to have to use the aux tank frequently so it keeps all the parts like the pump working well? Water pumps work best when they are active, otherwise they fail much sooner. Not sure if aux pump works similarly.

I don't think you HAVE to, but I would say regular use is a good thing as you point out in your example. For me part of the attraction is fewer trips to the gas station, so my SOP is to fill everything and run both dry. I've gone less than a day on a full fill of both tanks and also over a month without needing to fill up - depends on usage.

 

[clearmysix]

I think I have the answer to my fuel smell after the LRA install. I don't think there is a solution in my case and I think this is entirely expected from the LRA tank install.

The red circle is the filter that is put onto the end of the charcoal filter breather tube that vents air/gas fumes from the gas tank. For instance, when filling the tank you need to displace air/fumes inside the gas tank so this is where that air/fumes escape. I believe this end is usually tapped into an area on the filler tube (now replaced with the metal Y filler tube in the picture) and only vents when the tank is being filled with gas and closed off when the gas cap is on.

However in this altered configuration the gas cap never caps the end and it constantly emits a small amount of gas fumes from the vehicle.

The only way to stop this is to cap the breather and vent it only when needed. Unfortunately its not easily accessible in this location and so a modification would be necessary to cap the breather tube somewhere accessible.

Hope that helps those that have these. Let me know if you think I am wrong or have other suggestions.

 

[clearmysix]

Here is the schematic showing the above breather tube terminating in the filler tube instead of being open to air.

 

[TeCKis300]

Here is the schematic showing the above breather tube terminating in the filler tube instead of being open to air. View attachment 2904660

I use to believe that it was terminated in the filler neck, until I cut up the stock one. It's not. Wish I can find the picture at the moment, but it's terminated to a plastic collar around the stock filler neck, open to air. There's no actual pluming into the actual filter neck. What's ingenious about the design is that the airflow from the collar will vent into the gas pump vapor recovery when filling. And it's pretty well designed to handle dust/dirt ingress.

When the gas cap is on, it vents to atmosphere.

 

[grinchy]

So the LRA filler is designed differently?Stock system is closed at the fuel filler when the cap is on.
The charcoal canister routes to atmosphere via a filter, post the charcoal. It also routes to the manifold.
The vent line is hardline to the top of the filler, theoverflow holes behind the gas cap are also to the filler.
I guess this helps explain the different plumbing for the LRA.

 

[bloc]

The whole point of the charcoal canister is to aDsorb the fuel vapors and prevent them escaping to atmosphere. The problem is the canister will get "loaded up" with those vapors and needs to periodically be flushed of those vapors, usually by reversing normal outward flow back inward to the intake manifold where the vapors get burned and pass through the catalyst.

So it is totally normal for a charcoal canister to have a vent to atmosphere.. but that canister needs a way to be back flushed or eventually it'll just be vapors passing right through it.

Seems like I've seen a few other threads where the vapor problem was solved by raising that filter as high as possible. This strikes me as a different issue.

 

[Wisluggo]

In my 2019, with my 24gal LRA tank, I too get a faint fuel smell. It is almost always present but I have 15k miles on the tank since the install and there have been no codes

 

[TeCKis300]

So the LRA filler is designed differently?Stock system is closed at the fuel filler when the cap is on.
The charcoal canister routes to atmosphere via a filter, post the charcoal. It also routes to the manifold.
The vent line is hardline to the top of the filler, theoverflow holes behind the gas cap are also to the filler.
I guess this helps explain the different plumbing for the LRA.

View attachment 2904715

View attachment 2904717

I can't completely wrap my head around this as there's so many lines, but something on the OEM aux configuration plumbs into the filler? Isn't that the vent line from the tank rather than the breather of the charcoal canister? I thought this config never had a charcoal canister? Where do you have your canister breather plumbed to?

The USDM stock config with charcoal canister definitely does not plumb into the filler neck. Ward Harris from Cruiser Bros had to convince me of that when we were debugging the fill restriction issue. It plumbs outside of it as I wrote above. Was able to find this pic where I cut it up to confirm.

EDIT: This image may help

 

[grinchy]

I agree, the vent line goes into the neck at the filler. it is closed behind the gas cap.
The evap line goes into the canister, and out either to atmo (via the filter, post charcoal), or to the manifold.

What I was disagreeing with is that the vent line is open to atmo, which I thought it wasn't, unless the gas cap is off.

However, it looks like per the pic you put up, that that 'fat' line up by the filler is going into the plastic, and the plastic housing does not go back into the filler tube. I have mine old filler here, I'll go take a look at it at lunch, but that's a new view for me.

In the photo above the shiny (OEM Dual tank) filler does not have this plastic housing around the main filler . . .

 

[Angelo1]

I think I have the answer to my fuel smell after the LRA install. I don't think there is a solution in my case and I think this is entirely expected from the LRA tank install.

The red circle is the filter that is put onto the end of the charcoal filter breather tube that vents air/gas fumes from the gas tank. For instance, when filling the tank you need to displace air/fumes inside the gas tank so this is where that air/fumes escape. I believe this end is usually tapped into an area on the filler tube (now replaced with the metal Y filler tube in the picture) and only vents when the tank is being filled with gas and closed off when the gas cap is on.

View attachment 2904619

However in this altered configuration the gas cap never caps the end and it constantly emits a small amount of gas fumes from the vehicle.

The only way to stop this is to cap the breather and vent it only when needed. Unfortunately its not easily accessible in this location and so a modification would be necessary to cap the breather tube somewhere accessible.

Hope that helps those that have these. Let me know if you think I am wrong or have other suggestions.

That’s an interesting filter. This is what mine looks like. Also, check to make sure the drain bolt under tank isn’t dripping/seeping gas. LRA uses Teflon on the bolt threads and it doesn’t last very long. I attached a photo of what to use on the threads. Hope this helps. FYI-mine was leaking almost unnoticeable and produced a gas smell. It was a very slow drip.

 

[clearmysix]

That’s an interesting filter. This is what mine looks like. Also, check to make sure the drain bolt under tank isn’t dripping/seeping gas. LRA uses Teflon on the bolt threads and it doesn’t last very long. I attached a photo of what to use on the threads. Hope this helps. FYI-mine was leaking almost unnoticeable and produced a gas smell. It was a very slow drip.

View attachment 2904895

View attachment 2905133

Pretty install!

My tank isn't the source of the smell. Its at the area of the dual filler neck.

 

[Tex68w]

That’s an interesting filter. This is what mine looks like. Also, check to make sure the drain bolt under tank isn’t dripping/seeping gas. LRA uses Teflon on the bolt threads and it doesn’t last very long. I attached a photo of what to use on the threads. Hope this helps. FYI-mine was leaking almost unnoticeable and produced a gas smell. It was a very slow drip.

View attachment 2904895

View attachment 2905133

I wish I could get details on the hose and fittings used to upgrade this kit. I plan to install a LRA at some point in the near future and I want to upgrade the hoses before it's installed.

 

[Angelo1]

Pretty install!

My tank isn't the source of the smell. Its at the area of the dual filler neck.

Thank you! Hopefully you get it sorted out. Please let us know when you get resolved.

I wish I could get details on the hose and fittings used to upgrade this kit. I plan to install a LRA at some point in the near future and I want to upgrade the hoses before it's installed.

call Eric at Ed Martin Toyota.

 

[grinchy]

Ok. I had a look at the fuel filler routing diagram and the actual filler again to refresh my memory.
The 'stock' vent goes direct uninterrupted from the tank to the filler at 'fill' level, and is behind the fuel cap.
The 'stock' charcoal canister goes out to atmo from the canister via the charcoal and paper filter, to a tube that goes into the plastic around the filler tube as @TeCKis300 indicates. This plastic piece is always exposed to atmo at the edge of the filler; it is not behind the fuel cap like the vent is. It is behind the fuel filler door, but I doubt that provides an air seal. Since it is okay for this to vent to atmo (past the charcoal substrate), it is a nice detail that it is up by the fuel cap, but shouldn't affect vapor presence.

 

[TeCKis300]

Thanks for confirming @grinchy

So the question remains why the OP is experiencing this issue. The stock setup is no different in that the charcoal canister breather is open to atmosphere.

@clearmysix , are you having any fill issues? Any CELs? Or have you had any issues in the past? Wondering if your charcoal canister is fouled in some way and saturated with fuel. It probably is by the smell issue, which leads me to...

Possibility that the evap system is not working right in some way as it should be regularly purging to "recharge" the canister by vacuuming the fumes into the intake system. It's wholly possible something in the line, vacuum switching valve (VSV), or electrical plug/harness is damaged causing that not to happen.

 

[BlackMammoth]

I have the 40 gallon LRA - No fuel smell.

Was installed by Slee and I believe they replace all of the LRA provided hoses and just use the dual filler neck.

 

[grinchy]

Here is the schematic showing the above breather tube terminating in the filler tube instead of being open to air. View attachment 2904660

the charcoal canister (post charcoal) to plastic/fiber filter (77706) is at atmo already, as the connection to 77201 is thru a plastic ring around the filler pipe that does NOT go into the filler pipe, but instead vents freely behind the fuel filler door.
Sorry I didn't catch you had posted this earlier in the discussion.