LRA aux tank and slight gas smell

[bloc]

All of this is causing me to wonder if this was a big reason the OEM aux tank doesn't have a transfer phase.. you fill both.. then as fuel is used from the main it is backfilled via jet siphon from the aux. This way you only have evaporation happening from the surface of the fuel in the aux tank, then when it is empty, the main tank starts lowering, causing that surface to start producing vapors. The only time you'd be making vapors from both is if you filled them partially.. at which point the main would fill itself as quickly as it could.

Any thoughts @grinchy ?

 

[bloc]

Seems odd that I, and end user, have to be figuring this out for LRA... so be it.

I completely agree.

 

[TeCKis300]

Hey there 200 Series people. Here's my proposed "OEM-Isolated LRA Aux 24 System", which I hope will solve the evap/vent issues, plus all the other issues that the Australians didn't work out for us Americans on the 100 Series. This system will, I suspect, not meet US emissions regulations, due to the Aux tank vent directly to atmosphere, but I don't give a s*** after what I've been through. The Oregon DEQ can suck it. And I'm adding a 2nd charcoal canister for the Aux tank to help out with that.

Please let me know if anyone has any ideas/improvements. We are the last hope for 2004-2007 100 Series owners who want this system and it's range. This schematic is actually from the 200 series LRA install manual, which they also use for the 100 series....

View attachment 2943150

View attachment 2942571

View attachment 2943151

Hate to say this, as you've obviously put some effort into this. It's not going to work for several of the reasons already mentioned. There's also some fundamental flaws in this as the charcoal canister breather *has* to be plumbed to atmosphere. Otherwise, you're going to experience additional issues like engine unable to draw fuel as it will build vacuum (which will also further cause the fuel to boil).

Peeking over at the 100-series forum thread, I recommend you take @J1000 s lead. That is again the root issue. It's not fundamentally an LRA aux tank issue unless it just puts the system over the heat threshold.

The 200-series vehicles have also seen similar issues aux tank or not. Under armor. Low speed crawling. Even user things like not using low range which builds heat in the engine, transmission, and also causes the engine driven fan to not work as effectively as it would at high RPM in low range.

IIRC from my '06, the later model years didn't include a A/C condenser fan. That may also be one of the contributors to airflow and heat saturation.

IMO, it's not the 2-speed fuel pump. Not the LRA.

 

[porkandcorn]

Hate to say this, as you've obviously put some effort into this. It's not going to work for several of the reasons already mentioned.

All good, man. If I knew 100% what I was doing, I wouldn't be on here! All these ideas are being considered, without any concern for my own ego or half-baked plans.

 

[grinchy]

All of this is causing me to wonder if this was a big reason the OEM aux tank doesn't have a transfer phase.. you fill both.. then as fuel is used from the main it is backfilled via jet siphon from the aux. This way you only have evaporation happening from the surface of the fuel in the aux tank, then when it is empty, the main tank starts lowering, causing that surface to start producing vapors. The only time you'd be making vapors from both is if you filled them partially.. at which point the main would fill itself as quickly as it could.

Any thoughts @grinchy ?

Yeah, I don’t know. Maybe?
I know when Doing my install and the evap was open to atmo no charcoal canister that it created quite a lot of fumes, I ended up putting a plastic bag over it with a rubber band. My opinion is it will smell more than @porkandcorn bargains for.

If it was me, I’d ditch the entire install, sell it, and use the proceeds to buy a single larger tank like I linked earlier.

For whatever reason this truck doesn’t like it’s aux tank. My theory is it has to do with the main tank or main tank plumbing. That is the constant in all the changes.

 

[TeCKis300]

All good, man. If I knew 100% what I was doing, I wouldn't be on here! All these ideas are being considered, without any concern for my own ego or half-baked plans.

Thanks for that. I really do want to see you find that happy place and I will offer whatever insight I may have to help you find that. I've had my share of challenges being the first LX570 in North America to install an LRA so I've had to work through a few things.

And because misery loves company, I'm working on this over the weekend. Not for the same issue. I've got a small evap leak CEL and I'm overdue for smog. Not sure that it's the evap canister yet, but if I'm going to pull the LRA, I'm going to have parts on hand whatever it turns out to be.

 

[grinchy]

Thanks for that. I really do want to see you find that happy place and I will offer whatever insight I may have to help you find that. I've had my share of challenges being the first LX570 in North America to install an LRA so I've had to work through a few things.

And because misery loves company, I'm working on this over the weekend. Not for the same issue. I've got a small evap leak CEL and I'm overdue for smog. Not sure that it's the evap canister yet, but if I'm going to pull the LRA, I'm going to have parts on hand whatever it turns out to be.
View attachment 2943511

That sucks.

 

[TeCKis300]

All of this is causing me to wonder if this was a big reason the OEM aux tank doesn't have a transfer phase.. you fill both.. then as fuel is used from the main it is backfilled via jet siphon from the aux. This way you only have evaporation happening from the surface of the fuel in the aux tank, then when it is empty, the main tank starts lowering, causing that surface to start producing vapors. The only time you'd be making vapors from both is if you filled them partially.. at which point the main would fill itself as quickly as it could.

Any thoughts @grinchy ?

Vapor pressure doesn't depend on surface area. For a given liquid, it's vapor pressure depends on temperature.

I think what you're getting at is that a larger surface area can produce vapors more quickly. I don't believe that's the issue here. The evap canister is overwhemed on boiling events that exceed the vapor pressure handling of the fuel system, rather than nominal vapor pressures.

 

[bloc]

I think what you're getting at is that a larger surface area can produce vapors more quickly.

That exactly. I haven’t been tracking all the details of this thread but killing charcoal canisters with aux tanks even without known boiling events seems like something I read about. Or even people like me that have boiled fuel multiple times but not killed a CC.. yet anyway.

I was just wondering out loud if Toyota’s strategy for transferring fuel was partly reliability, convenience and simplicity, but maybe also had some evaporative emissions benefit as well.

 

[Fisher23]

IMHO the OEM evaporation cannister is designed for a tank with "x" gallons and then when you triple or double the tanks it's overloaded.
I think changing the programming of the evap. system would solve the issue.

Keep in mind the LRA tanks were made and designed for the diesel system without the evap. system attached.

 

[bloc]

IMHO the OEM evaporation cannister is designed for a tank with "x" gallons and then when you triple or double the tanks it's overloaded.
I think changing the programming of the evap. system would solve the issue.

That’s my point though. Yes, the CC is different in this setup, but the switchover strategy of the stock aux tank system means most of the time only one tank is producing vapors.

As long as they aren’t boiling. Which I personally believe toyota didn’t plan for.. allowing that to happen is not a good way to manage evaporative emissions which is a primary goal of modern emissions systems.

 

[CharlieS]

I don't discount the fact that many people have had issues, but my one data point is that I haven't had any issues in the time that I've had mine installed. No fumes, no codes, no leaks. I definitely haven't done any high altitude or high temperature driving, so those may be big factors. I am running the @TeCKis300 mod with larger vent line and K&N vent filter.

 

[porkandcorn]

I don't discount the fact that many people have had issues, but my one data point is that I haven't had any issues in the time that I've had mine installed. No fumes, no codes, no leaks. I definitely haven't done any high altitude or high temperature driving, so those may be big factors. I am running the @TeCKis300 mod with larger vent line and K&N vent filter.

Bear in mind, I'm a 100 series owner, and beyond that I have a 2006. Toyota made significant changes to the 100 Series evap system somewhere in 2004, which lead to LRA no longer providing support to 100's of those model years. In fact, the distributors have been instructed by LRA not to sell the 40g or 24g Aux to anyone without providing their vin number to insure they do NOT own LC's in those productions year. I *think* they made changes again in 2008 with the switch to the 200s.

I know.... what is this hundy owner doing over here on the two-hundy forum.... that said, some of my best input for solutions is coming from here.

 

[porkandcorn]

Vapor pressure doesn't depend on surface area. For a given liquid, it's vapor pressure depends on temperature.

I think what you're getting at is that a larger surface area can produce vapors more quickly. I don't believe that's the issue here. The evap canister is overwhemed on boiling events that exceed the vapor pressure handling of the fuel system, rather than nominal vapor pressures.

My evap can was fouled on all 3 occassions without boiling events. I suspect it's getting liquid fuel in the vent lines due to the poor design of the dual fill neck for the 100 series. The 200 fill neck is redesigned to address these issues. Consequently, I'm modifying my neck to move these vent bung up high on the filler neck body. Imagine the gas station pump - you put it in this thing to fill as LRA sent it, and it's basically blasting fuel straight down the vents. I measured, and that is right where the gas pump nozzle sits inside the neck.... such a terrible design and I can hardly believe they would let people buy it.

 

[TeCKis300]

My evap can was fouled on all 3 occassions without boiling events. I suspect it's getting liquid fuel in the vent lines due to the poor design of the dual fill neck for the 100 series. The 200 fill neck is redesigned to address these issues. Consequently, I'm modifying my neck to move these vent bung up high on the filler neck body. Imagine the gas station pump - you put it in this thing to fill as LRA sent it, and it's basically blasting fuel straight down the vents. I measured, and that is right where the gas pump nozzle sits inside the neck.... such a terrible design and I can hardly believe they would let people buy it.

View attachment 2943805

That is a bit weird that the vent line positions are in the fill tubes. That is definitely different than the config of the 200-series fill neck which looks much more like what you're proposing.

I believe you're aware, those vents don't plumb to the evap, but to each respective tank. I believe the responsibility of those vents is to help the fuel fill pump sense full and shutoff. If I understand the system, the way each works is that there's a float on the tank end, that will close the vent upon full. It may be with what you're saying, that fuel get blasted into those ports. The issue could be that it doesn't shut-off the pump correctly, overfilling the tanks, that then fouls the evap canister?

Postulating aside, the 200-series stock fill neck does seemingly have the vent port close to the fill nozzle?

EDIT: Adding pic of 200-series stock fill neck

 

[porkandcorn]

That is a bit weird that the vent line positions are in the fill tubes. That is definitely different than the config of the 200-series fill neck which looks much more like what you're proposing.

I believe you're aware, those vents don't plumb to the evap, but to each respective tank. I believe the responsibility of those vents is to help the fuel fill pump sense full and shutoff. If I understand the system, the way each works is that there's a float on the tank end, that will close the vent upon full. It may be with what you're saying, that fuel get blasted into those ports. The issue could be that it doesn't shut-off the pump correctly, overfilling the tanks, that then fouls the evap canister?

Postulating aside, the 200-series stock fill neck does seemingly have the vent port close to the fill nozzle?

A bit weird is very diplomatic - you're a kind man. I would say "idiotic". I edited my post above to include a shot of my modified 100 series neck, and 2 images of the 200 neck - it's vent bungs are properly located from LRA.

Yes, they plumb to the tanks, and as I understand it, their purpose is to let air out of the tanks as you fill them. Gas in - air out. Otherwise you back up and have fill issues like I have had.

 

[CharlieS]

Bear in mind, I'm a 100 series owner, and beyond that I have a 2006. Toyota made significant changes to the 100 Series evap system somewhere in 2004, which lead to LRA no longer providing support to 100's of those model years. In fact, the distributors have been instructed by LRA not to sell the 40g or 24g Aux to anyone without providing their vin number to insure they do NOT own LC's in those productions year. I *think* they made changes again in 2008 with the switch to the 200s.

I know.... what is this hundy owner doing over here on the two-hundy forum.... that said, some of my best input for solutions is coming from here.

It is a 200 problem too. I'm just trying to understand out why some people have it and others don't. Temperature, elevation, fuel blend???? I'm glad I don't, but wish we knew why so we could prevent it across the board. These things really need an aux tank the way they guzzle gas.

 

[porkandcorn]

These things really need an aux tank the way they guzzle gas.

Indisputable truth!!!

 

[porkandcorn]

The issue could be that it doesn't shut-off the pump correctly, overfilling the tanks, that then fouls the evap canister?

One preventative measure for all of us, is to NEVER top of the tanks. My buddy has a 200, and he determined he was flooding his smaller charcoal canister at the gas station, trying to top off his tank.

 

[FerrisBueller]

Data point for stock tank, no customizations to fuel system. I definitely starting having a boiling gas issue today. Admittedly, I had mindlessly used some lower quality gas earlier this week and probably still had about a 50% mix of that in the tank.

Edit: this is in Texas @ Hidden Falls Adventure Park

It didn't "pour" out of the fill area per se, just a few drops dripped down past the door. But I had started smelling gas pretty strongly right before so I checked as soon as I could. When I went next to the gas cap I could hear it hissing and see fumes escaping pretty rapidly.

90 degrees outside wasn't too extreme, but the boiling happened when I had just taken a few difficult (to me) obstacles and then idled for like 30 minutes in one spot without any breeze / airflow (waiting for others to take an obstacle). I'm convinced it's heat / airflow issue (maybe gas quality is secondary issue).

I made sure to turn off the vehicle anytime I was waiting for others, and the problem went away.

You can see the couple drips out the bottom of the door, and the fumes in this picture.