LRA aux tank and slight gas smell

[bloc]

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.

This makes me wonder what feedback system the ecu has to tell when the CC is saturated. It’s simple to put it on a timer and let purging happen when it thinks it should need it, but surely there is some system to tell the ecu and trigger a code if the CC gets overwhelmed.

Actually this may be what is happening with the Moab code..

Also, you guys with LRAs have significantly increased the surface area of the fuel in the tanks, which is correlated with increased rate of evaporation. At some point the CC may not be designed to handle that volume of vapor. Then again plenty of people run LRA without issue.

Is there any correlation with LRA fuel vapor smell in places with higher ambient temperatures, seasonal, etc?

 

[TeCKis300]

This makes me wonder what feedback system the ecu has to tell when the CC is saturated. It’s simple to put it on a timer and let purging happen when it thinks it should need it, but surely there is some system to tell the ecu and trigger a code if the CC gets overwhelmed.

Actually this may be what is happening with the Moab code..

Also, you guys with LRAs have significantly increased the surface area of the fuel in the tanks, which is correlated with increased rate of evaporation. At some point the CC may not be designed to handle that volume of vapor. Then again plenty of people run LRA without issue.

Is there any correlation with LRA fuel vapor smell in places with higher ambient temperatures, seasonal, etc?

I'll need to dig in more, but I'm pretty sure I remember the EVAP system has self test routines. For the purge valve circuit. Which is why I'm wondering if there CELs. But wholly possible there's a failure mode that's undetectable. Like a flooded or worn charcoal canister that can no longer absorb vapors? That's it's job after all, and why modern cars don't smell like old pre-emissions cars.

 

[grinchy]

I've added in this diagram how the OEM sub tank is routed (in red).

I have suspicions only (read opinion) that not having the evap chain thru the tanks in serial is putting a lot of vapor pressure at the fuel cap (high point of the system). So the 'upgraded' hoses, fittings, schmoo etc (and definitely a new fuel cap O ring) are employed to keep that vapor pressure in the sealed portion of the system -> No smell.

As soon as there is a small sealing issue then this vapor pressure is partially escaping and the install smells.

The other issue is that there is no direct evap path to build vacuum in the sub tank. Is this an issue? Maybe not, maybe the various interconnected vents (at top of filler behind fuel cap) is 'the same'. Maybe not.

Lots of installs of LRA, very few issues . . .

 

[clearmysix]

I want to thank everyone for taking the time to correct my assumptions and give me more information to potentially solve this issue.

I do not have any CELs. I have put about 7000 miles on the LRA tank without ever having a CEL.

As for filling I do occasionally have an issue completely filling the tank because the gas nozzle shuts off early and won't pump more. I would say it has happened about 10-20% of the time. I usually can get about 50+ gallons in but sometimes the last 5-10 can be an issue, but other times it all just flows perfectly.

As for the smell, to better characterize it. It is coming from right around the dual filler neck to the best that I can tell. It doesn't matter if the tanks has 60 gallons in it or 3 gallons (empty AUX) - I still can smell it. That being said, both shops I have taken the truck to initially cannot smell it - so it is subtle.

If this is from a flooded charcoal canister wouldn't I get a CEL? I think that might be the last thing I replace since it would require me to drop the aux tank.

 

[Fisher23]

The other issue is that there is no direct evap path to build vacuum in the sub tank. Is this an issue? Maybe not, maybe the various interconnected vents (at top of filler behind fuel cap) is 'the same'. Maybe not.

I tried t-tapping the main and aux vents together and then running them into the evap but then I got another issue. The problem I got was when filling the aux tank there was not enough venting to fill at normal speed and could only fill at the slow fill rate.
I did this a long time ago .. got one of the first tanks before they came out with good instructions.


I would also get codes that way. Not every day but frequently.

So I went back to the diagram way with larger vent hoses and now I still get codes but they are occasionally. Like once every couple weeks and mostly when cold at night.

I do not get vapor smell, just codes.

The system does not have problem building pressure. It has a problem over-night.

I did try checking the gas cap in the mornings to see if the valve was sticking and keeping pressure over night, but it was not. When I stop and turn off the vehicle and check.. there is no pressure just like it should be.

I also looped the main tank vent up and over the top if the fill cap area just incase I forget to turn off the aux pump, that way it would not over fill the evap can.

 

[Julian73]

Does anybody have or can diagram the schematic of the OEM venting/fill system and the hybrid OEM dual tank system that @grinchy is using.

 

[grinchy]

Fun with diagrams for @Julian73

 

[Fisher23]

@grinchy so you are thinking the aux tank should have another hole in the top and this should "T"-tap into the evap. line? Maybe that would fix my codes that I get occasionally.

I'm not sure about altering the main tank vent to "T" tape into the aux tank as before when I did that the main tank had issues with the filling speed.

 

[grinchy]

I'm not sure where to start. Perhaps list the codes - there are codes for unable to set the test vacuum on the comparison oriface (large leak), and then vacuum run down tests (small leak). Which type of codes are you seeing?
Obviously the LRA sub tank isn't directly connected to evap, whether this actually is an issue or not, it is hard to say, there are many successful installs; and designing these things is above my pay grade.

 

[Angelo1]

I had a fuel smell so bad, I had to kick the 200 outside. I swore up and down it was coming from the canister or fuel neck. Eric from Ed Martin took it back to work on. He went above and beyond trying to figure the cause of smell. Literally replaced everything with high end parts, new evap, etc. The only item that was not replaced, the aux tank. He took the 200 home and garaged it to make sure it was not producing any smell. The following day it was good to come back home. Very excited on my end, I finally receive it and goes right into garage. I wake up the next morning and dammit!, gas smell all over again. Got back on the phone with Eric and he reached out to Ward and LRA. Everyone was dumbfounded as the install was top notch and lines run correctly. The following day I walk outside and see a brown wet mark under the truck. Sure enough, it’s gas. The dang bolt was allowing the smallest drip because LRA uses Teflon tape on the treads and it doesn’t last. Eric sent me prime seal gasket sealant type 3. Worked like a charm! That minuscule drip that was undetectable finally showed it’s face and was causing the smell in my garage. All good now. I think we will always have a hint of fuel smell but now my 200 is allowed back in the garage.

Please check your drain bolt!

 

[clearmysix]

I had a fuel smell so bad, I had to kick the 200 outside. I swore up and down it was coming from the canister or fuel neck. Eric from Ed Martin took it back to work on. He went above and beyond trying to figure the cause of smell. Literally replaced everything with high end parts, new evap, etc. The only item that was not replaced, the aux tank. He took the 200 home and garaged it to make sure it was not producing any smell. The following day it was good to come back home. Very excited on my end, I finally receive it and goes right into garage. I wake up the next morning and dammit!, gas smell all over again. Got back on the phone with Eric and he reached out to Ward and LRA. Everyone was dumbfounded as the install was top notch and lines run correctly. The following day I walk outside and see a brown wet mark under the truck. Sure enough, it’s gas. The dang bolt was allowing the smallest drip because LRA uses Teflon tape on the treads and it doesn’t last. Eric sent me prime seal gasket sealant type 3. Worked like a charm! That minuscule drip that was undetectable finally showed it’s face and was causing the smell in my garage. All good now. I think we will always have a hint of fuel smell but now my 200 is allowed back in the garage.

Please check your drain bolt!

Thank you for your rec! It’s crazy it seems like there are 100 things that can cause this symptom with these tanks.

My bolt is dry and I got my nose right up to it and it’s not where the gas smell is from. It’s from the area of the fuel neck.

 

[grinchy]

Thank you for your rec! It’s crazy it seems like there are 100 things that can cause this symptom with these tanks.

My bolt is dry and I got my nose right up to it and it’s not where the gas smell is from. It’s from the area of the fuel neck.

View attachment 2908241

Try the recommended schmoo above on the vent fittings

 

[bloc]

@grinchy so you are thinking the aux tank should have another hole in the top and this should "T"-tap into the evap. line? Maybe that would fix my codes that I get occasionally.

I'm not sure about altering the main tank vent to "T" tape into the aux tank as before when I did that the main tank had issues with the filling speed.

If the AUX and main tank both have their fill vent line (orange in above diagram) there shouldn't be a need for an evap line from the AUX to the charcoal canister. Any vapors from the aux tank should make it to the fill neck and down into the top of the main tank via that orange vent line.

That said.. this assumes there are no valves or anything controlling the direction of flow in those vent lines.

 

[grinchy]

Yep, that makes sense, the vapor pressure should be the same at all places in a connected system.

Here’s a pic from inside the oem sub tank of the evap pipes. Whatever it’s doing, it isn’t as simple as a bung at a high point.
My assumption is there is a reason to build all this piping inside the tank, maybe to meet emissions, maybe to make it work, who knows.
All we can gather from the oem design is that it routes evap separately from vent, and has evap on each tank.
I will again say I’m not trying to disrespect the aftermarket tanks. This here discussion is only about trying to find the root cause for the smell.

 

[bloc]

Yep, that makes sense, the vapor pressure should be the same at all places in a connected system.

Here’s a pic from inside the oem sub tank of the evap pipes. Whatever it’s doing, it isn’t as simple as a bung at a high point.
My assumption is there is a reason to build all this piping inside the tank, maybe to meet emissions, maybe to make it work, who knows.
All we can gather from the oem design is that it routes evap separately from vent, and has evap on each tank.
I will again say I’m not trying to disrespect the aftermarket tanks. This here discussion is only about trying to find the root cause for the smell.

View attachment 2908296

I'm assuming your ability to get more pictures of this was limited by access..

Really would like to know what's going on in there. Maybe it has to do with fuel sloshing somehow?

And evap lines off both tanks could simply be to meet some regulation. Though the complexity of that system clearly has some purpose.

 

[grinchy]

I was able to fit an old small iPhone in the hole the siphon fits to. I have a video somewhere, basically the evap pipe goes around the entire internal perimeter of the tank. I was curious which fitting should be evap ‘in’ vs ‘out’. It didn’t matter as they both went to the same pipe about 6” apart, at the same level. The evap piping wasn’t all the way at the top of the tank, more top third, and don’t appear perforated.

 

[grinchy]

Here’s the video

 

[Angelo1]

Thank you for your rec! It’s crazy it seems like there are 100 things that can cause this symptom with these tanks.

My bolt is dry and I got my nose right up to it and it’s not where the gas smell is from. It’s from the area of the fuel neck.

View attachment 2908241

Interesting your drain bolt is located on the side of tank. Mine is underneath. Maybe why yours looks so clean

 

[Fisher23]

The evap line is lower so that "hot" fuel going back in is cooled.

I wonder how the EVAP system on the FORD pickups with dual tanks is plumbed?

 

[bloc]

I was able to fit an old small iPhone in the hole the siphon fits to. I have a video somewhere, basically the evap pipe goes around the entire internal perimeter of the tank. I was curious which fitting should be evap ‘in’ vs ‘out’. It didn’t matter as they both went to the same pipe about 6” apart, at the same level. The evap piping wasn’t all the way at the top of the tank, more top third, and don’t appear perforated.

Yeah this must be some method of separating liquid from vapor.

Also this isn't helping me resist installing the OE subtank as you did..