Gas/Fuel vapors/fumes visible from gas door (2 Viewers)

[indycole]

Most likely more of an issue on heavily built trucks like yours that require more horsepower to punch a hole through the 80mph air than stock.. which is how toyota gets away with this per EPA/CARB.

Then again plenty of people tow heavy…

Yeah, that could definitely play a role... or even the additional armor under storing some heat? I don't recall ever having boiling gas on the highway when I just had sliders and 33s; however, that's exactly the setup I had the first time I experienced it on Top of the World. Everyone's gas was boiling that day across a variety of builds.

The thing that really sucked about boiling gas on the highway is that I could not transfer fuel from the aux tank to the main due to the pressure. I was on a remote stretch of road just last summer where I had counted on being able to use that extra fuel. It just wouldn't go into the main tank. I really regretted not having the awning on the truck that day as it took ~1.5 hrs for the gas to cool down with ambient temps of ~110 in Nevada.

Interestingly, the temps I monitor (coolant, transmission, intake) weren't really any higher than usual. I think I'm going to put a thermocouple on the outside of the fuel tank and start tracking some data on this.

 

[linuxgod]

I posted this in another thread, and I've noted this before

If you're seeing boiling gas, try a tank of premium. I've anecdotally found I hardly ever need to vent my rotopax when I used 93 octane from BP last year, but when I kept 87 in it the summer before I have to vent it daily. Far far less swelling with 91. I had the rotopax of 87 spray out on me upon opening once as it was boiling inside, but I went almost 3 weeks in CO last year both sitting in the sun at the sand dunes and at 10,000' elevation in White River NF and I had no issues.

YMMV of course, but at the moment I'm convinced it would likely reduce or eliminate this issue.

 

[linuxgod]

Yeah, that could definitely play a role... or even the additional armor under storing some heat? I don't recall ever having boiling gas on the highway when I just had sliders and 33s; however, that's exactly the setup I had the first time I experienced it on Top of the World. Everyone's gas was boiling that day across a variety of builds.

The thing that really sucked about boiling gas on the highway is that I could not transfer fuel from the aux tank to the main due to the pressure. I was on a remote stretch of road just last summer where I had counted on being able to use that extra fuel. It just wouldn't go into the main tank. I really regretted not having the awning on the truck that day as it took ~1.5 hrs for the gas to cool down with ambient temps of ~110 in Nevada.

Interestingly, the temps I monitor (coolant, transmission, intake) weren't really any higher than usual. I think I'm going to put a thermocouple on the outside of the fuel tank and start tracking some data on this.

Quick answer would be to carry an IR thermometer and just zap it with a laser occasionally and record the temp.

 

[kreiten]

Yeah, that could definitely play a role... or even the additional armor under storing some heat? I don't recall ever having boiling gas on the highway when I just had sliders and 33s; however, that's exactly the setup I had the first time I experienced it on Top of the World. Everyone's gas was boiling that day across a variety of builds.

The thing that really sucked about boiling gas on the highway is that I could not transfer fuel from the aux tank to the main due to the pressure. I was on a remote stretch of road just last summer where I had counted on being able to use that extra fuel. It just wouldn't go into the main tank. I really regretted not having the awning on the truck that day as it took ~1.5 hrs for the gas to cool down with ambient temps of ~110 in Nevada.

Interestingly, the temps I monitor (coolant, transmission, intake) weren't really any higher than usual. I think I'm going to put a thermocouple on the outside of the fuel tank and start tracking some data on this.

Weight could be an issue as I have been all through Death Valley, across Utah and Nevada more times than I can count and my rig has never had it happen on the HWY(mine is pretty light). For me the issue only has happened in Moab, my theory is elevation, heat and shaking.

 

[kreiten]

My daughter's boyfriend is a mastertech at Toyota and he said he had not seen this issue or heard about it... I have been dealing with this since 2016 and sadly have just learned to live with it

 

[kalieaire]

Yeah, that could definitely play a role... or even the additional armor under storing some heat? I don't recall ever having boiling gas on the highway when I just had sliders and 33s; however, that's exactly the setup I had the first time I experienced it on Top of the World. Everyone's gas was boiling that day across a variety of builds.

The thing that really sucked about boiling gas on the highway is that I could not transfer fuel from the aux tank to the main due to the pressure. I was on a remote stretch of road just last summer where I had counted on being able to use that extra fuel. It just wouldn't go into the main tank. I really regretted not having the awning on the truck that day as it took ~1.5 hrs for the gas to cool down with ambient temps of ~110 in Nevada.

Interestingly, the temps I monitor (coolant, transmission, intake) weren't really any higher than usual. I think I'm going to put a thermocouple on the outside of the fuel tank and start tracking some data on this.

What platform are you using for data logging?

 

[grinchy]

This series is the best I've found on detailed information regarding the Toyota (Lexus, Scion) evap system. I did a deep dive while installing my sub tank trying to understand the ramifications of relocating the canister to the engine bay.

Part 1 has some background 7 min thru 15 min. then you can skip to part 2, which is the system on the 200s.

 

[isthatalexus]

Imma reach way back to my PC overclocking days and say: big copper water-cooling slug with 24" radiator on the back of the spare tire swing-out. Yes, it adds 250 lbs, but LC200.

 

[unclemat]

I am in Moab now. Drove through Denver yesterday and have the same dreaded issue!

First smell and visible traces of gas leaking from the fuel door. Running 87 octane, and in fact I had a mix of pure 87 gas and E10 87 before climbing the mountains yesterday. Smell occurred right after Denver when we stopped for coffee. Just highway driving, nothing else.

Filled up with pure 87 gas along the way. Today in Moab I had maybe 3/8 of tank left, filled up with 91 E10 up to ~3/4 of full just in case. Smelled a lot of gas on a trail today, small traces visible at the fuel door but no where near as bad as yesterday.

I never overfill the truck, stop at first click. Granted bought it used @ 50k miles (now 73k), so who knows how the previous owner used to fill it up. So, yeah, I wonder about the condition of the charcoal can now.

Anyway, this is pretty pathetic that the King of the (off) road can't handle some altitude. Piss poor job, Mr. T!

 

[kalieaire]

I think this is one of the reasons California's gas is the way it is especially during the summer. We switch to, albeit more expensive, a summer blend of gasoline which reduces the amount of highly volatile hydrocarbons like butane. Butane, for example, is a cheap yet high octane component of conventional gasoline with a low boiling temp. Under favorable atmospheric conditions (such as heat and temperature), it can easily flash off in the state of Colorado.

 

[vegasfj40]

Wow. Havent experienced this yet with my 21 HE. This engine is available in the Middle East isnt it? It's gotta be the amount of ethanol in our gas. Surprised to hear about this on the 200s.

 

[TeCKis300]

It's an issue with the fuels in the US. The volatility and gas vapor pressure is regulated by the EPA. Known as Reid Vapor Pressures (RVP).

Simplified explanation​

EPA regulates RVPs to either 7.8PSI and 9 PSI (@100 °F) depending on region and season. Generally, summer blends have lower RVP requirements (to protect fuel loss to atmosphere). Winter, higher RVP (as gas is less volatile in lower temps and this helps starting).

EPA also allows an additional 1 PSI margin higher for ethanol blends.

Other factors - 87 octane tends to have higher vapor pressures. 91, lower. Higher octane is naturally more stable with combustion inhibitors, and less volatile. Another way to say it is that higher octane fuels tend to have less light end petroleum components - the stuff that tend to vaporize easily.

Takeaways​

- Use high octane fuel even if your vehicle may not call for it
- Avoid ethanol blends
- Get local gas from higher elevations as its likely blended for the higher altitude locale
- I would not recommend opening the gas cap as the system pressure can help it from over-boiling. Relieving the pressure in only going to increase boiling and vaporization. It's normal for the gas tank to vent once it exceeds it's safe design pressure and that's likely designed into the cap

Slow vehicle operation, high weather temps, and increase altitude will all increase fuel volatility.

 

[tbisaacs]

I am in Moab now. Drove through Denver yesterday and have the same dreaded issue!

First smell and visible traces of gas leaking from the fuel door. Running 87 octane, and in fact I had a mix of pure 87 gas and E10 87 before climbing the mountains yesterday. Smell occurred right after Denver when we stopped for coffee. Just highway driving, nothing else.

Filled up with pure 87 gas along the way. Today in Moab I had maybe 3/8 of tank left, filled up with 91 E10 up to ~3/4 of full just in case. Smelled a lot of gas on a trail today, small traces visible at the fuel door but no where near as bad as yesterday.

I never overfill the truck, stop at first click. Granted bought it used @ 50k miles (now 73k), so who knows how the previous owner used to fill it up. So, yeah, I wonder about the condition of the charcoal can now.

Anyway, this is pretty pathetic that the King of the (off) road can't handle some altitude. Piss poor job, Mr. T!

I just got back from Moab and had the same issues. Strong smell, vapor puking out. No codes (knock on my wood steering wheel)

 

[kreiten]

It's an issue with the fuels in the US. The volatility and gas vapor pressure is regulated by the EPA. Known as Reid Vapor Pressures (RVP).

Simplified explanation​

EPA regulates RVPs to either 7.8PSI and 9 PSI (@100 °F) depending on region and season. Generally, summer blends have lower RVP requirements (to protect fuel loss to atmosphere). Winter, higher RVP (as gas is less volatile in lower temps and this helps starting).

EPA also allows an additional 1 PSI margin higher for ethanol blends.

Other factors - 87 octane tends to have higher vapor pressures. 91, lower. Higher octane is naturally more stable with combustion inhibitors, and less volatile. Another way to say it is that higher octane fuels tend to have less light end petroleum components - the stuff that tend to vaporize easily.

Takeaways​

- Use high octane fuel even if your vehicle may not call for it
- Avoid ethanol blends
- Get local gas from higher elevations as its likely blended for the higher altitude locale
- I would not recommend opening the gas cap as the system pressure can help it from over-boiling. Relieving the pressure in only going to increase boiling and vaporization. It's normal for the gas tank to vent once it exceeds it's safe design pressure and that's likely designed into the cap

Slow vehicle operation, high weather temps, and increase altitude will all increase fuel volatility.

I ran the highest octane I could get in Moab and didn't help at all, I've run 1/4, 1/2 full tank etc, from the fleet of rigs we have put through the Moab trails nothing seemed to help! The cap does release fuel all over the place even with it fully on, like ya said that's part of the system. And when I say release fuel I'm not talking about drops, I've been behind rigs that dumped fuel, like a cup or 2 going over an obstacle... is what it is I guess

 

[kreiten]

I just got back from Moab and had the same issues. Strong smell, vapor puking out. No codes (knock on my wood steering wheel)

View attachment 2737947

knock on wood is a good call buddy! Everyone else had pretty much gotten the dreaded Moab code and as I drove home I thought damn I got lucky! 1 week later the code popped, F**K! Fingers crossed for ya!

 

[TeCKis300]

I ran the highest octane I could get in Moab and didn't help at all, I've run 1/4, 1/2 full tank etc, from the fleet of rigs we have put through the Moab trails nothing seemed to help! The cap does release fuel all over the place even with it fully on, like ya said that's part of the system. And when I say release fuel I'm not talking about drops, I've been behind rigs that dumped fuel, like a cup or 2 going over an obstacle... is what it is I guess

Agreed and I don't believe there's a single silver bullet here. Gas will do what gas was designed to do - vaporize. Add in enough temperature and altitude and it boils. It doesn't take much and components of gasoline will boil at just a bit over 100 °F. Which in Moab with lots of slow speed maneuvering, with hot engine and exhaust radiating underneath, is not hard to exceed.

It's not a solution but the points above may help manage the degree of boiling. Actually, more gas in tank may help to some extent too as it has more thermal mass to dampen temps. But run slow and long enough, and even a full tank of gas will heat up.

Gasoline doesn't have a single boiling point as its a blend. The light end petroleum hydrocarbon components will gas and boil off first. If one lets their gas tank boil all that off, it'll solve the problem eventually, but will lose a good volume of gasoline that was paid for.

Maybe that could be part of the solution. To vent the cap tank regularly on the way up before it's a boiling mess? Gasoline disappearing to thin air be damned.


...diesel won't boil until much higher temps. Maybe we need one of those?

 

[04UZJ100]

Agreed and I don't believe there's a single silver bullet here. Gas will do what gas was designed to do - vaporize. Add in enough temperature and altitude and it boils. It doesn't take much and components of gasoline will boil at just a bit over 100 °F. Which in Moab with lots of slow speed maneuvering, with hot engine and exhaust radiating underneath, is not hard to exceed.

It's not a solution but the points above may help manage the degree of boiling. Actually, more gas in tank may help to some extent too as it has more thermal mass to dampen temps. But run slow and long enough, and even a full tank of gas will heat up.

Gasoline doesn't have a single boiling point as its a blend. The light end petroleum hydrocarbon components will gas and boil off first. If one lets their gas tank boil all that off, it'll solve the problem eventually, but will lose a good volume of gasoline that was paid for.

Maybe that could be part of the solution. To vent the cap tank regularly on the way up before it's a boiling mess? Gasoline disappearing to thin air be damned.


...diesel won't boil until much higher temps. Maybe we need one of those?

Agree in principle - three main things that affect volatility of hydrocarbons: temperature, pressure, and grade/blend. However, I’d like to at least think that EPA specs for RVP and TVP are in alignment with DoT/Manufacturer specifications with regards to normal altitude and temperature changes found within the US. The NHTSA, DOT, EPA, etc do NOT want fuel boiling out of gas caps on the regular from any car - especially those traversing normal interstates during 4 seasons of weather.

Which leads me to believe Toyota is either too conservative with how much pressure their trying to maintain in our fuel tanks and/or, the temperature of the returned fuel to the thank is hotter than reasonably believed to be within federal regulations and design considerations leading to the problems that we see across the 100 and 200 series. If the pressure is trying to be maintained at a threshold to minimize vapors escaping the tank and the system is overwhelmed due to temperature and or pressure changes, it’s incorrectly designed. Likewise, if the fuel returned to the thank is too warm (from routing near the block/exhaust) that is a design issue as well.

I would think the NHSTA and DoT would take this seriously if elevated among the appropriate channels to see if Toyota comes up with a true reason why it’s occurring.

Further, I bet if someone tubes up a VPSV (vacuum and pressure safety valve) on their fuel tank upstream of their carbon filter - the issue would go away. Needs to be set a a few inches, if that, of water column from a relief standpoint.

 

[unclemat]

The issue seems to be affecting mostly Land Cruisers for some reason. Googling "Moab gas boiling" get you this subforum as 2nd top hit. Otherwise some bikes seem to have the problem. Does not seem to be affecting Jeeps, even 4Runners, or Tacos.

Almost as if Toyota hacked up EVAP system for USDM 200-series and did not test it thoroughly enough. If this issue was affecting 4Runners, there is no way there wouldn't be a fix - too many sales on the line. 200-series owners who dare to venture outside mall parking lots need to suck it up apparently.

Now experiencing it, the issue to be honest bugs me greatly. Gas staying inside the tank is kinda fundamental requirement of a well functioning vehicle. Most other quirks, limitations, or reliability issues can be dealt with. A basic design issue like this is a serious problem.

 

[TLC2013]

In regards to octane rating and vapers. Has anyone experimented with using a good octane booster or adding some race fuel to bump up the levels ? I wonder if this would result in a reduction or fully elimnate the boiling issue?

 

[unclemat]

From what I read that's not quite possible - gasoline is a blend of various components, and some have lower boiling point than others, and can "boil" independently. Mixing in something else won't affect those. But then I know zero about gasoline chemistry.