Here I wonder if it's boiling or just under too much pressure?
LRA aux tank and slight gas smell
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Here I wonder if it's boiling or just under too much pressure?
Thanks for the clarifications. I'm really grateful to everyone here for their contributions.
Maybe restating a few ways could help?
Added heat into the fuel system, to the extent of boiling, is what causes pressure. That is the root issue. Heated fuel generates more vapor pressure. Boiling fuel causes a lot of vapor pressure.
Pressure does not create heat. Pressure can be helpful as it actually suppresses vapor pressure and increases the boiling temperature of fuel. Pressure in itself does not heat or boil fuel, and therefore is not the root issue.
Pressure is a symptom of overheated fuel. Not the other way around.
I had a brand new evap canister installed on my 3rd round. All with the same end results, FYI.
Markuson
SILVER Star
Once again…reports of Utah fuel doing this is the strangely common denominator.. I’ve had boiling gas about 8 or 9 times over the years (both after and BEFORE LRA), and without exception, its been in Utah…including moderate altitude, non-climbs, and moderate temps (but in high temps and steep climbs more common(.
In contradt… In Californua…blasting up mountains near Stockton when its 112 degrees at altitude? Nothing. -No boiling. My own local desert in serious heat… nothing. But out on the flats at highway speed in Utah? Boiling like crazy.
Need to make a poll where people entder the state their fuel is from… From my own rough observations, its massively tilted toward Utah…despite cColorado and California also having hot, high altitude drives.
In contradt… In Californua…blasting up mountains near Stockton when its 112 degrees at altitude? Nothing. -No boiling. My own local desert in serious heat… nothing. But out on the flats at highway speed in Utah? Boiling like crazy.
Need to make a poll where people entder the state their fuel is from… From my own rough observations, its massively tilted toward Utah…despite cColorado and California also having hot, high altitude drives.
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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.
Dunbar
SILVER Star
Add aux electric fan to cool the tank(s) and or lines and components?
Well I was thinking if that evap hose it not routed correctly and has been routed to the filler instead of the atmosphere, then there is no escape for the pressure.
So I was thinking 1 of 2 things is going on.
If the Evap line is routed wrong Even if the valve is working and opens it is going to open the evap line to the enclosed filler area. Then no escape for the pressure.
or 2. The Evap line is routed correctly but the valve is not working.
Since he installed a new evap box, likely #1. Evap line routed incorrectly.
Even if the fuel was "hot" I would look at that as a 2nd issue .. and the pressure should still escape if the evap line is routed correctly and the valve is working correctly.
That is my understanding of it.
Do you have any install pics showing the lines?
Have you considered replacing with an oem sub tank?
Have you considered removing the 2nd tank and reverting to stock.
Have you replaced all the stock vent lines (maybe one is clogged)?
How much is a stock main tank? Maybe consider this?
What’s the chassis code on your 100? I want to look at a parts diagram and try to understand the stock routing.
Have you considered replacing with an oem sub tank?
Have you considered removing the 2nd tank and reverting to stock.
Have you replaced all the stock vent lines (maybe one is clogged)?
How much is a stock main tank? Maybe consider this?
What’s the chassis code on your 100? I want to look at a parts diagram and try to understand the stock routing.
It has to do, I think , with the local fuel stocks and additives. Utah (and some places in CO ) have some incredibly low octane gas and (relatively) low winter temps. I crawl a heavy load lx in the sierras (much lower elevation from CO) and the 110F at 80 mph too, and never once had this issue. Sunoco Race Fuels - https://www.sunocoracefuels.com/tech-article/octane-stability-high-octane-vs-low-octane-fuels
Or consider something like this?
Markuson
SILVER Star
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.
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Would using premium fuel in the Aux tank help prevent boiling or vapors during the summer? If pure gas gas is available, would this be the best aux tank option?
I don’t believe the octane makes much difference as long you are dealing with conventional gasoline from a filling station.
Race fuel will be different - there are wildly different blends. It is possible to buy unleaded race fuel that has the same spec as AVGas (see next paragraph).
AVGas (aviation fuel) is specifically designed to be resistant to boiling (pressure at high altitude is much lower) however almost all of it is leaded and will destroy your catalyst and O2 sensors. We run AVGas in everything that doesn’t have a catalyst.
As far as regional gas variations - I am not a petroleum guy but I believe it has due with what hydrocarbons are used to make up gasoline - some are more resistant to vaporizing than others.
The times the bubbling has happened to me I just let it go until it ceased. Phase change cooling is very effective.
While I don't know that regular octane fuel is the issue here, I will say that in my limited anecdotal experience, higher octane fuel resists vaporizing better. There's probably a term for this I don't know.
When I first started keeping a rotopax on my roof during long trips I would fill it with 87 octane need to vent it daily. One trip I was coming from Denver to Ouray and was going to stop in Jefferson, CO for gas; however the only gas stations in town were permanently closed at the time. I pulled the rotopax off the roof to add to the tank and fuel sprayed out when I cracked it open. I would've called it "boiling" but I'm not actually sure that's a true statement. Regardless the temp and elevation was a problem.
The last 2 years when I've taken trips I've put 93 octane from my local Shell station here near Chicago in the rotopax before leaving (10% ethanol mix). On a 5 week trip last year I vented it maybe 3 or 4 times. It would bulge a bit sometimes but never boiled or sprayed out. Maybe it's the octane rating, maybe it's the Chicago gas mix, who knows? Keep in mind the rotopax is sitting on the roof so (1) it gets direct sun baking it all day, and (2) any air in it get spread across the entire container (similar to a gas tank) instead of the usual vertical 'pax mount where only the top has an air gap.
The only time I've ever noticed gas vapors coming out of the cap I was running 87 octane and towing up into the mountains in Grand Mesa, CO. I stopped for a photo op as I was approaching 10,000' and I could smell gas. That was a few years ago. This summer I ran premium in my tank while I was in Moab last August. I did White Rim over 2 days (about 100 miles) normal driving around town, plus a couple hours on Fins N Things, and I never had any gas boiling issues. But this is all extremely anecdotal of course.
Again for the regularity you're seeing this problem I'm not suggesting your issue is regular vs premium. However if anyone is only occasionally seeing this problem, particularly at high elevations (or in Moab) I'd suggest at least trying to switch to the highest octane fuel you can find for those trips.
When I first started keeping a rotopax on my roof during long trips I would fill it with 87 octane need to vent it daily. One trip I was coming from Denver to Ouray and was going to stop in Jefferson, CO for gas; however the only gas stations in town were permanently closed at the time. I pulled the rotopax off the roof to add to the tank and fuel sprayed out when I cracked it open. I would've called it "boiling" but I'm not actually sure that's a true statement. Regardless the temp and elevation was a problem.
The last 2 years when I've taken trips I've put 93 octane from my local Shell station here near Chicago in the rotopax before leaving (10% ethanol mix). On a 5 week trip last year I vented it maybe 3 or 4 times. It would bulge a bit sometimes but never boiled or sprayed out. Maybe it's the octane rating, maybe it's the Chicago gas mix, who knows? Keep in mind the rotopax is sitting on the roof so (1) it gets direct sun baking it all day, and (2) any air in it get spread across the entire container (similar to a gas tank) instead of the usual vertical 'pax mount where only the top has an air gap.
The only time I've ever noticed gas vapors coming out of the cap I was running 87 octane and towing up into the mountains in Grand Mesa, CO. I stopped for a photo op as I was approaching 10,000' and I could smell gas. That was a few years ago. This summer I ran premium in my tank while I was in Moab last August. I did White Rim over 2 days (about 100 miles) normal driving around town, plus a couple hours on Fins N Things, and I never had any gas boiling issues. But this is all extremely anecdotal of course.
Again for the regularity you're seeing this problem I'm not suggesting your issue is regular vs premium. However if anyone is only occasionally seeing this problem, particularly at high elevations (or in Moab) I'd suggest at least trying to switch to the highest octane fuel you can find for those trips.
bloc
SILVER Star
I have it most times I go to colorado and do the high passes, on a totally stock fuel system. I can't remember if there is a correlation to getting ethanol-free fuel in durango.. not that there is, or isn't. I just can't remember.
This is only tangentially related, but shows how regional differences in fuel can be present. In common rail TDI VWs there was a rash of high pressure fuel pump failures, and this was attributed to the diesel lubricity standard in the US barely hitting Bosch's requirements, as compared to europe where it was exceeded, and almost no HPFP failures. As people analyzed the data they found that very generally speaking, the closer you were to a coast, the less likely you were to have a pump failure. Live in the interior? More common.
Which simply shows fuel can change properties, additives, and composition by region. Not to mention for emissions reasons in states like california with such tight regulation on evaporative emissions.
Interesting ... I noticed that only Utah allows E15 vs E10 in the gasoline and possibly that higher percentage of Ethanol is the cause?
Not all places in Utah put in E15 but many cities do.
Ethanol
Ethanol is a renewable fuel made from corn and other plant materials. The use of ethanol is widespread, and more than 98% of gasoline in the U.S. contains some ethanol. […]
utahcleancities.org
Remember that you can make "Gasoline" with a wide variety of vapor pressures - that is a separate issue from the addition of Ethanol. So, just looking at the label and seeing 10% Ethanol isn't giving you the whole story.
Gasoline Reid Vapor Pressure
Gasoline Reid Vapor Pressure
