Evap Codes GONE...Woo! **UPDATE... Codes back...

[linuxgod]

Boiling gas in extreme heat and altitude in Moab. We believe it fouls the charcoal canister, but there may be more to it...such as a fuel filler hose that is not air tight.

Given you guys had gas boiling out of the tanks (which are supposed to be sealed), and I believe @Atwalz replaced his charcoal canister but still had codes, I suspect the pressure causes a weld to crack or some other failure which results in a tiny vapor leak. Just a hunch but replacing your filler nozzle is what I suspect actually solved your issue.

 

[Atwalz]

Given you guys had gas boiling out of the tanks (which are supposed to be sealed), and I believe @Atwalz replaced his charcoal canister but still had codes, I suspect the pressure causes a weld to crack or some other failure which results in a tiny vapor leak. Just a hunch but replacing your filler nozzle is what I suspect actually solved your issue.

I no longer have any codes.

 

[Markuson]

Given you guys had gas boiling out of the tanks (which are supposed to be sealed), and I believe @Atwalz replaced his charcoal canister but still had codes, I suspect the pressure causes a weld to crack or some other failure which results in a tiny vapor leak. Just a hunch but replacing your filler nozzle is what I suspect actually solved your issue.

I don’t think Atwalz replaced his filler neck...

 

[Atwalz]

I don’t think Atwalz replaced his filler neck...

I didn’t replace filler neck. I did replace new OE canister, evaporator hoses and vapor filter.

 

[GeorgeN]

I changed the charcoal canister right after returning from Telluride and so far so good, no more error codes. Let’s hope it will last.

 

[Mendocino]

I continue to have this issue. It was most pronounced last August (2019) on the White Rim Trail in Canyonlands. I regularly get the P0441 code. Today I got the P2420 code. I replaced the charcoal cannister after the White Rim trip, but am still getting the codes. I will replace the fuel cap and keep working to sort this out.

 

[empty80]

I’ve had the P043E, P043F, P0456, P2401, P2402 and P2419 since my tank was installed. Seems like my error code grab bag is outside on the normal reference for this issue. I suspect it has something to do with this gem...

Can you fine gentlemen confirm if this was part of your install?

 

[Markuson]

I had forgotten about this thread that is now pretty outdated. I have mentioned it elsewhere… But it is worth noting hear that my codes have returned after significant boiling gas issues in Utah again. Those actually reappeared over a year ago in Utah. Also worth mentioning, though, is that I see no link between the presence of my auxiliary tank… And no auxiliary tank. Bubbling gas has led to codes both before my auxiliary tank… And after my auxiliary tank. This is clearly an issue that affects many 200 series drivers regardless of whether they have an auxiliary tank or not.

 

[kcruiser200]

I had forgotten about this thread that is now pretty outdated. I have mentioned it elsewhere… But it is worth noting hear that my codes have returned after significant boiling gas issues in Utah again. Those actually reappeared over a year ago in Utah. Also worth mentioning, though, is that I see no link between the presence of my auxiliary tank… And no auxiliary tank. Bubbling gas has led to codes both before my auxiliary tank… And after my auxiliary tank. This is clearly an issue that affects many 200 series drivers regardless of whether they have an auxiliary tank or not.

@Markuson ... so, is this an issue even with regular use or specifically related to high altitude / high ambient temperature wheeling?? I am assuming the latter based on your comments.

 

[kcruiser200]

I’ve had the P043E, P043F, P0456, P2401, P2402 and P2419 since my tank was installed. Seems like my error code grab bag is outside on the normal reference for this issue. I suspect it has something to do with this gem...View attachment 2325213

Can you fine gentlemen confirm if this was part of your install?

is this a new part on the 2016+ cruisers?? There have been quite a few small updates even after 2016 that have not been advertised by toyota. Wonder if they have new checks / nannies on the fuel system to monitor for added tanks n such?? I am by no means an expert , just speculating I guess

 

[Markuson]

@Markuson ... so, is this an issue even with regular use or specifically related to high altitude / high ambient temperature wheeling?? I am assuming the latter based on your comments.

I personally have experienced before and after the sub tank...so that tells me it is not caused by, not specific to sun tank installs. Others I k ow have experienced it before and/or after as well...all invluding boiling gas at high altitude.

I have only ever experienced boiling gas when fueled up in Utah. No proof of cause there, as it also happens to be the location of very hot, slow, steep climbs in Moab.

 

[kcruiser200]

I personally have experienced before and after the sub tank...so that tells me it is not caused by, not specific to sun tank installs. Others I k ow have experienced it before and/or after as well...all invluding boiling gas at high altitude.

I have only ever experienced boiling gas when fueled up in Utah. No proof of cause there, as it also happens to be the location of very hot, slow, steep climbs in Moab.

allrite --- note to self - strap on some dry ice packs over main and aux tanks when in moab!!! just kidding.... but that also means that I would need to familiarize myself with the nitty-gritties of sub tank installs. even though I won't be doing this myself, it will be good to know if I ever need to trouble shoot or drop the tank for access to the charcoal canister.

 

[Markuson]

allrite --- note to self - strap on some dry ice packs over main and aux tanks when in moab!!! just kidding.... but that also means that I would need to familiarize myself with the nitty-gritties of sub tank installs. even though I won't be doing this myself, it will be good to know if I ever need to trouble shoot or drop the tank for access to the charcoal canister.

Honestly… Probably the best answer is to just keep a code-read and reset capable OBDII unit available. Clearing codes and good to go takes all of about 15 seconds...evenwhile driving if i don’t see before getting under way... No need to stop or shut off.
$30-50.

 

[kcruiser200]

Honestly… Probably the best answer is to just keep a code-read and reset capable OBDII unit available. Clearing codes and good to go takes all of about 15 seconds...evenwhile driving if i don’t see before getting under way... No need to stop or shut off.
$30-50.

which tool do you use?? I use Carly on my other car, although admittedly I havent had to use it much (knock on wood!!!). But, more importantly, clearing codes is one thing --- but you still have to fix the fault that caused the codes in the first place no?? Not an issue if its a temporary issue that goes away once the offending cause is resolved. BUt if its an actual functional / structural fault, then that would need to be fixed too, which in todays vehicles is a royal PITA!!!

 

[linuxgod]

I had forgotten about this thread that is now pretty outdated. I have mentioned it elsewhere… But it is worth noting hear that my codes have returned after significant boiling gas issues in Utah again. Those actually reappeared over a year ago in Utah. Also worth mentioning, though, is that I see no link between the presence of my auxiliary tank… And no auxiliary tank. Bubbling gas has led to codes both before my auxiliary tank… And after my auxiliary tank. This is clearly an issue that affects many 200 series drivers regardless of whether they have an auxiliary tank or not.

Anecdotally, I recommend trying premium fuel when you're going up in elevation or wheeling in really hot temps like Utah. I had some boiling fuel at the top of Grand Mesa (10k feet) a couple years back - enough that you could smell fuel when I stopped to take a photo. I also vented my rotopax and had fuel spray out at a different point (and when I finally did get it open the fuel was boiling inside). Fast forward to last year where I ran premium all trip and I didn't have that issue, and the rotopax hardly seemed to expand at all and required very little venting. (Side note: I put my rotopax on the roof so it's mounted horizontally).

My assumption about the above situation is that higher octane fuel is just a bit less combustible, and so there's less vaporization. I'd love someone with a chemical engineering degree to explain the above better. But 2 years ago I had to vent the rotopax every day in CO when I had regular gas in it, yet last summer I vented it a fraction of the number of times and each time it was just a little "puff" of air.

I normally run 87 here at near sea level in the midwest, but when I'm towing I've taken to running 91 - and always keeping 91+ in the rotopax.

@Markuson in your case I don't know if running the expensive stuff will help alleviate the issue in the future, but if the codes are extremely intermittent you might give it a whirl.

 

[4gotalot]

I am a mechanic not a chemist but my bet is that some of these problems are from the ethanol.

I have been doing some testing with fuel that has "no ethanol" 91 octane. 91 octane is the only way we can fuel with out ethanol around here. The trails I have been testing go up to 9000ft and the fuel is definitely shaken not stired. Other trips are at 5000ft but still have had venting issues and shaken fuel but no codes so I have been able to repeat the same trail with different fuel. All of my data is going to Taco2cruiser.

 

[kcruiser200]

Anecdotally, I recommend trying premium fuel when you're going up in elevation or wheeling in really hot temps like Utah. I had some boiling fuel at the top of Grand Mesa (10k feet) a couple years back - enough that you could smell fuel when I stopped to take a photo. I also vented my rotopax and had fuel spray out at a different point (and when I finally did get it open the fuel was boiling inside). Fast forward to last year where I ran premium all trip and I didn't have that issue, and the rotopax hardly seemed to expand at all and required very little venting. (Side note: I put my rotopax on the roof so it's mounted horizontally).

My assumption about the above situation is that higher octane fuel is just a bit less combustible, and so there's less vaporization. I'd love someone with a chemical engineering degree to explain the above better. But 2 years ago I had to vent the rotopax every day in CO when I had regular gas in it, yet last summer I vented it a fraction of the number of times and each time it was just a little "puff" of air.

I normally run 87 here at near sea level in the midwest, but when I'm towing I've taken to running 91 - and always keeping 91+ in the rotopax.

@Markuson in your case I don't know if running the expensive stuff will help alleviate the issue in the future, but if the codes are extremely intermittent you might give it a whirl.

this is interesting. would be good to compare the hygroscopic qualities of both fuels as well as ethanol content - this may influence the amount of water each retains (increased water/moisture absorption in ethanol containing fuels is well known). I dont know if regular vs premium grade affects the amount of moisture that can be absorbed for the same molar content of ethanol in each grade. This may affect the boiling point. Does anyone know if premium grade has an inherent higher boiling point (not combustible threshold which speaks to the fuel actually igniting)?

Here's another thought - when you reference "boiling" - is it really boiling?? or is it bubbling due to "off-gassing " of dissolved gases at high altitude which in turn is also increased by the higher temperature that the fuel is sitting at?? Essentially, per gas laws - higher temperature and lower ambient pressures speeds up the exit of dissolved gases from a given liquid. I wonder if the index of phase separation of dissolved gas from fuel is different between the 2 grades of fuel??

@linuxgod .. what you seem to describe does point to a difference in an "off-gassing" quotient between regular and premium grades of fuel. I have always wondered why the LX comes specified with premium grade recommendation and the LC with regular grade recommendation for exactly the same engine. Maybe their charcoal canister OR evap systems have minor differences that account for the different fuel grade recommendations. Just a thought.

 

[linuxgod]

this is interesting. would be good to compare the hygroscopic qualities of both fuels as well as ethanol content - this may influence the amount of water each retains (increased water/moisture absorption in ethanol containing fuels is well known). I dont know if regular vs premium grade affects the amount of moisture that can be absorbed for the same molar content of ethanol in each grade. This may affect the boiling point. Does anyone know if premium grade has an inherent higher boiling point (not combustible threshold which speaks to the fuel actually igniting)?

Here's another thought - when you reference "boiling" - is it really boiling?? or is it bubbling due to "off-gassing " of dissolved gases at high altitude which in turn is also increased by the higher temperature that the fuel is sitting at?? Essentially, per gas laws - higher temperature and lower ambient pressures speeds up the exit of dissolved gases from a given liquid. I wonder if the index of phase separation of dissolved gas from fuel is different between the 2 grades of fuel??

@linuxgod .. what you seem to describe does point to a difference in an "off-gassing" quotient between regular and premium grades of fuel. I have always wondered why the LX comes specified with premium grade recommendation and the LC with regular grade recommendation for exactly the same engine. Maybe their charcoal canister OR evap systems have minor differences that account for the different fuel grade recommendations. Just a thought.

Bubbling maybe? Hard to tell through the fill spout.

Intuitively it feels like it should make a difference, since we know low octane fuel can combust at lower temps (engine knocking) than high octane fuel does. Whether it's actually boiling point, or flash point, or something else I'm not sure.

I can't really decipher this at the moment but a quick google search says it does Correlation Between the Octane Number of Motor Gasoline and Its Boiling Range

Octane number as a function of boiling range
The octane number decreases in general with increasing boiling range [1], [2]. This. effect is, however, different for different types of fuel. It is more pronounced for straight-run gasoline [2]. This is probably due to greater variation in the composition of straight-run gasolines as compared to reformate or racked gasoline.

Also Pressure and temperature effects on fuels with varying octane sensitivity at high load in SI engines (no good quote)

The premium I bought last year was from the local service station, so it was 10% ethanol.

 

[kcruiser200]

Bubbling maybe? Hard to tell through the fill spout.

Intuitively it feels like it should make a difference, since we know low octane fuel can combust at lower temps (engine knocking) than high octane fuel does. Whether it's actually boiling point, or flash point, or something else I'm not sure.

I can't really decipher this at the moment but a quick google search says it does Correlation Between the Octane Number of Motor Gasoline and Its Boiling Range

Octane number as a function of boiling range
The octane number decreases in general with increasing boiling range [1], [2]. This. effect is, however, different for different types of fuel. It is more pronounced for straight-run gasoline [2]. This is probably due to greater variation in the composition of straight-run gasolines as compared to reformate or racked gasoline.

Also Pressure and temperature effects on fuels with varying octane sensitivity at high load in SI engines (no good quote)

The premium I bought last year was from the local service station, so it was 10% ethanol.

so, if this study is accurate - not considering ethanol in the mix - if lower octane number corresponds to a lower boiling point and a higher octane number corresponds to a higher boiling point , then the observations of regular grade gasoline boiling in MOab at altitude (low pressure) and in high temperature environment can be explained. especially if the incidence of this happening on premium grade fuels is lower. And it does not even have to be a gross boiling I am assuming to throw codes. If, Even small bubbles appearing anywhere in the fuel system (lines, canister, etc) are detected by sensors, then this may cause relevant codes.

And if this theory is actually true - then it should also affect the way the engine will operate - cause if the fuel is bubbling, considering that the NA motor is also operating at a lower atmospheric pressure, there is the risk of inappropriate fuel delivery by injectors with bubbled fuel. combine that with increased risk of knock from high altitude and lower octane ---- you get my drift.