LRA aux tank and slight gas smell

[TeCKis300]

Yes. Same. Never in CA, Baja, or Nevada. Nor Canada, OR, WA, CO, OH, AZ, NM, TX, WY, WI, ID, MO.

Just Utah 8-9 times.

There's likely something to this. There's different formulation requirements for vapor pressure depending on local and season. There's an additional 1.0 psi relaxing of requirements for ethanol. All of CAs formulations have even stricter guidelines than federal requirements. Excerpts from the reference linked below. Lower vapor pressure number is desirable. Note these ratings are per standard conditions (i.e. 100F). Hotter or boiling fuel is going to increase pressures.

Full reference here

Gasoline Reid Vapor Pressure | Gasoline Standards | US EPA

19january2017snapshot.epa.gov

 

[TeCKis300]

How about this most important question: What are the shops in the Pacific NW, or Mountain West if I have to, who would be interested in helping me find a solution. I'm not a mechanic, I have no space to work on the vehicle, and I have only the most rudimentary understanding of these fuel/evap systems. My original installer isn't interested (justifiably) because they don't think they can improve my results, my dealership-based LC specialist said that he can't any longer be involved in a research/R&D project, and I even gave Slee Offroad a call and they said they are not putting LRAs in 100's anymore, nor interested in working on them, until the distributor and the Aussie's can resolve these issues. I'm up s*** creek. I have no paddle.

Speaking candidly. You've got a heat management issue. There's little doubt in my mind. Chasing symptoms won't fix this root issue. The second fill symptom also supports this as vapor pressure and boiling saturate the evap canister, making symptoms more obvious and worse.

1) Remove the under-armor. Straight forward and you might be able to see obvious differences immediately
2) Add fiberglass insulation I linked earlier to where the mufflers comes near the aux tank

 

[GTV]

Removing the skid plates would be an interesting and easy test. Actually, placing a temp sensor under there and collecting data would be even better.

Heat shield near the resonator couldn't hurt. But again I wonder, how is the factory sub tank any different? Or maybe it's apples vs oranges since those vehicles weren't fitted with U.S. emissions systems.

What about a return line fuel cooler?

 

[CharlieS]

As I recall, the factory tanks are plastic. Or am I misremembering?

 

[BlackMammoth]

As I recall, the factory tanks are plastic. Or am I misremembering?

For the 200 series yes they are plastic.

 

[bloc]

For the 200 series yes they are plastic.

The factory sub tank too? Looked metal to me.

 

[BlackMammoth]

The factory sub tank too? Looked metal to me.

There is no factory sub tank in the USA

 

[bloc]

There is no factory sub tank in the USA

Which is the exact reason people bother with LRA tanks.

Charlie didn’t specify which market he was referring to when he made that observation immediately after a post about the factory sub tank possibly being different.

 

[porkandcorn]

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....

 

[porkandcorn]

Speaking candidly. You've got a heat management issue. There's little doubt in my mind. Chasing symptoms won't fix this root issue. The second fill symptom also supports this as vapor pressure and boiling saturate the evap canister, making symptoms more obvious and worse.

1) Remove the under-armor. Straight forward and you might be able to see obvious differences immediately
2) Add fiberglass insulation I linked earlier to where the mufflers comes near the aux tank

I appreciate the idea. I didn't realize I would start a 3-page discussion on fuel boiling! It's actually the least of my worries, and entirely avoidable if I take more time to climb to elevation. In any case, I learn a lot about the fuel/evap system, so it's all good.

 

[grinchy]

If you're going to all the trouble to drop the tank and refit the filler, why not simply T the sub tank vent into the evap 'in'?
Then you can forgo the solenoids.

 

[porkandcorn]

If you're going to all the trouble to drop the tank and refit the filler, why not simply T the sub tank vent into the evap 'in'?
Then you can forgo the solenoids.

I'm trying to isolate to OEM system from the LRA system, except when filling up, or pumping from, the Aux tank, *if* I understand your idea. There are so many unknowns, that I'm taking the most conservative approach.

 

[Fisher23]

If you're going to all the trouble to drop the tank and refit the filler, why not simply T the sub tank vent into the evap 'in'?
Then you can forgo the solenoids.

My thoughts also, but i did get some codes doing it that way back when I originally got the tank.

The above proposed solution would not work as it doesn't allow either tanks to pressurize for the evap. system. The pressure would simply leak out the aux tank vent.

 

[bloc]

Plus the aux tank vent being wide open would just be releasing vapors and fuel smell everywhere.

 

[porkandcorn]

My thoughts also, but i did get some codes doing it that way back when I originally got the tank.

The above proposed solution would not work as it doesn't allow either tanks to pressurize for the evap. system. The pressure would simply leak out the aux tank vent.

Thanks for helping me vet this idea guys. Here's my thinking: The two 'Normally Closed' solenoids - one on the 1/4" output from the LRA tank to the OEM-side of the dual-filler neck, and the other on the 1" LRA-side input to the LRA tank seal the original OEM system off completely from the LRA system, and provide a pressured seal to allow the OEM evap system to function as designed, without throwing codes. There are no other common connections in my proposed system, and the 5/8" bung normally on the LRA-side of the dual filler is permanently sealed off. The solenoids are rated for both gaseous vapor and gal liquid, well above the normal pressure of the OEM evap system.

 

[porkandcorn]

Plus the aux tank vent being wide open would just be releasing vapors and fuel smell everywhere.

This is true. My thought is to keep the smaller charcoal canister, now located on the 5/8" vent line, and just before the mushroom filter. This should capture some, if not all, of the smell and vapor. I can live with some smell, if it means that the isolated OEM system will be fool-proof. Additionally, the LRA tank plumbed in the manner I proposed, will be empty and unused when I'm in daily driver mode, which is 75% of the year. I can always push all the fuel to the main tank, to keep smell down in my normal life.

 

[Fisher23]

This is true. My thought is to keep the smaller charcoal canister, now located on the 5/8" vent line, and just before the mushroom filter. This should capture some, if not all, of the smell and vapor. I can live with some smell, if it means that the isolated OEM system will be fool-proof. Additionally, the LRA tank plumbed in the manner I proposed, will be empty and unused when I'm in daily driver mode, which is 75% of the year. I can always push all the fuel to the main tank, to keep smell down in my normal life.

It will not work because it not a closed system. Evap. systems pressurize the system.

With what you have there, when the evap. pressurizes the main tank the pressure will flow back up to the gas cap and back to the aux tank and out the aux tank vent. Then you have fumes and an open system.

The code I get occationally is P0441.
Diagnostic trouble code (DTC) P0441 stands for “Evaporative Emission Control System (EVAP) Incorrect Purge Flow.” Your car's computer will set the code when it determines there's an improper amount of fuel vapor being “purged” from the EVAP charcoal canister into the engine.

 

[porkandcorn]

It will not work because it not a closed system. Evap. systems pressurize the system.

With what you have there, when the evap. pressurizes the main tank the pressure will flow back up to the gas cap and back to the aux tank and out the aux tank vent. Then you have fumes and an open system.

The code I get occationally is P0441.
Diagnostic trouble code (DTC) P0441 stands for “Evaporative Emission Control System (EVAP) Incorrect Purge Flow.” Your car's computer will set the code when it determines there's an improper amount of fuel vapor being “purged” from the EVAP charcoal canister into the engine.

Maybe I didn't explain something earlier very well. But, in the diagram, there are only 2 connections from the Aux tank to the OEM fuel system - which are both at the fill neck. When those 2 ball valves are closed, there is no connection to the Aux system, and the OEM system can pressurize as normal. The ball valves are vacuum-rated.

 

[Fisher23]

I understand,

When you are underway and transferring fuel the fuel system needs to be pressurized and sealed..
If you leave the filler ball valve closed when transferring fuel you risk flooding the evap. box.

It is an interesting idea, and very similar to how transfer-flow runs their aux tanks.
When refueling in your diagram the ball valve by the fuel pump is opened when given current.
When at rest and the engine is turned off the ball value on the aux filler opens when it doesn't have power.

What transfer-flow does is auto fill when the main is between 1/4 and 3/4. On the LRA tank controller the black and white wire is for this purpose.
When transfer-flow monitors the main tank level, then there is no risk of flooding the evap. system.
This is also how the military generators auto re-fill.

Yes it might work much better and not overload the evap. system.

 

[porkandcorn]

Ultimately, the isolated dual fuel systems is a last resort, IF my mods to the dual fuel neck do not solve the evap problems. Install and test the modified fuel neck first. If that fails, install the electronic valves and isolate the LRA system. Seems odd that I, and end user, have to be figuring this out for LRA... so be it.