Gas/Fuel vapors/fumes visible from gas door (1 Viewer)

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I had this issue with my 80 a lot also. Last time I had it in CO we were at about 10,000ft in the summer and when I removed the gas gap, fuel was literally spraying out of the tank and I could hear what sounded like boiling. It was pretty wild.

Haven't had the issue in the 200. But I don't go much over 5000ft these days and living in the PNW where it's a little cooler, so it hasn't been an issue. Yet.
 
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.

Pragmatically, I don't see a resolution. It's such a niche situation. Not like it's happening to cars driving down the highway or majority of trail runs. I just got back from a 10,000ft trail peak. No gas boiling to speak of.

It's specific to long hot temp slow crawl days. Sure, I agree with your sentiment, but the likelihood of hoping for anything to be done by the powers that be, especially for cars already on the road are likely nil.
 
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.

My GX 470 just did the same thing on a tough climb to 7800 ft. Off-gassing and the visible dirt drip down the side under the gas gap.
 
My GX 470 just did the same thing on a tough climb to 7800 ft. Off-gassing and the visible dirt drip down the side under the gas gap.
That sucks! Well, GX is Land Cruiser Prado after all, so you qualify, I guess :)

Btw, quick Googling does not yield gas boiling complaints in Tundra. Same powertrain like 200. I wonder how different fuel system is on Tundra. Larger tank on some (38 gal vs. 26 gal), that's all I know.
 
Pragmatically, I don't see a resolution. It's such a niche situation. Not like it's happening to cars driving down the highway or majority of trail runs. I just got back from a 10,000ft trail peak. No gas boiling to speak of.

It's specific to long hot temp slow crawl days. Sure, I agree with your sentiment, but the likelihood of hoping for anything to be done by the powers that be, especially for cars already on the road are likely nil.
I had it happen on normal highway drive on I-70 right after passing Denver (where we actually stopped for 1.5 hours, so the truck had a chance to cool). Granted the truck was fairly loaded. But I also have Budbuilt alu skid on the gas tank, so I am wondering if it is contributing. I have hard time beliving that these few holes in the factory skid would make such a difference.
 
Toyota Lexus uses the same charcoal can valve pump design in all its non EV/hybrid US cars. Since 2004 or something like that.
 
I think outside temp must have a lot to do with it. I did not have this problem when I was in Moab in April for Cruise Moab. I have BB skids and the 12.5 LRA tank.
 
Filled up today with ethanol free 91 in Moab, then again in Grand Junction, CO so my tank was pretty much 100% ethanol free. Drove back through mountains on pavement (route 141, then 90), then took trail towards Geyser Pass and La Sal Pass (both were sadly closed). When stopped at the approach to La Sal Pass I could smell gas strongly, but only small traces below fuel door.

Most of the pavement drive was hot (~96F) but as I climbed the mountains the temperature dropped to ~77F and then the smell dissipated. Started at ~4500 ft, end up at about ~8000 ft.

Point is that E0 91 + hot weather + altitude + 70 mph pavement driving + maybe half an hour of a 20 mph gravel road drive = still a problem.

This is unacceptable and makes me start question my choice of the vehicle. I wonder how the new HE would perform. Maybe I will find out next year.

The mega thread in 100-series section seems to say that it's combination of factors but the biggest offender is heating of the fuel in the lines that go close the cat. People apparently fashion some sort of heatshield.

Not sure how 200-series routes the fuel lines, will have to look next time. I wonder if my skids exacerbate the issue by keeping the heat in even more.
 
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It would be interesting to know where the system is venting from.

As I understand it, the charcoal canister VSV is open to atmosphere when the car runs. Which terminates on a plastic collar around the fuel filler neck. I don't know for sure, but the gas cap likely has a pressure relief threshold. Would it be venting via the charcoal or gas cap. It would be hard to distinguish.

@unclemat - do you have skids? Not sure how much of a problem they are but they likely don't help the situation?
 
FilledNot sure how 200-series routes the fuel lines, will have to look next time. I wonder if my skids exacerbate the issue by keeping the heat in even more.

@unclemat - do you have skids? Not sure how much of a problem they are but they likely don't help the situation?

Same thing on my truck. I also have the BB fuel skids.

* Edited to add since Rob chimes in - I had the same problem with the OEM skid. In general, I’m of the belief that’s it’s just an attribute of the overall system though I do like to entertain the idea that it’s the fuel.
 
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Filled up today with ethanol free 91 in Moab, then again in Grand Junction, CO so my tank was pretty much 100% ethanol free. Drove back through mountains on pavement (route 141, then 90), then took trail towards Geyser Pass and La Sal Pass (both were sadly closed). When stopped at the approach to La Sal Pass I could smell gas strongly, but only small traces below fuel door.

Most of the pavement drive was hot (~96F) but as I climbed the mountains the temperature dropped to ~77F and then the smell dissipated. Started at ~4500 ft, end up at about ~8000 ft.

Point is that E0 91 + hot weather + altitude + 70 mph pavement driving + maybe half an hour of a 20 mph gravel road drive = still a problem.

This is unacceptable and makes me start question my choice of the vehicle. I wonder how the new HE would perform. Maybe I will find out next year.

The mega thread in 100-series section seems to say that it's combination of factors but the biggest offender is heating of the fuel in the lines that go close the cat. People apparently fashion some sort of heatshield.

Not sure how 200-series routes the fuel lines, will have to look next time. I wonder if my skids exacerbate the issue by keeping the heat in even more.
Why would a HE be any different?
 
Did the fuel or evap system change at all on the 16 and up? There's a guy in our local Cruiser club with a 17. Its built up pretty heavy and he's out in the backcountry quite a bit. I need to ask him if he's experienced this yet.
 
I’m gonna say something that I’ve been working on for over a year now. It will not be received positively from the community. But please, understand that I’ve been taking measurements across over 80 200s under lot of conditions. It took me a long time to even accept this as I just didn’t feel the failure was what I “wanted to believe.”

Also, don’t take what I say as gospel, I would like to be proved wrong here. It frustrate me a lot on what I believe the issue is.

What I’ve found, is the following. Let go of anything aftermarket causing fuel boiling. Just let it go, it’s not the culprit. 200s have been boiling fuel long before most things were even available for our trucks. Elevation doesn’t necessarily matter. Ambient temp doesn’t necessarily matter. Fuel type and octane equivalent levels doesn’t necessarily matter. Emissions equipment doesn’t matter. Age sometimes matters, but I’ve seen plenty of brand new, bone stock 200s boil gas when off road or towing.

Toyota uses a return style fuel system. Just like on the 4.7L, Toyota found that it was best to run the fuel pump wide open. Then uses a fuel pressure regulator to manage the fuel needed for the motor. The extra goes back to the tank. BUT!!! This is where it gets interesting. They use the extra fuel to cool various components on the top end of the motor. Fuel is a hell of a cooling liquid and Toyota uses it, along with engine oil and coolant to keep their V8s from ever over heating.

So… when you are applying a lot of load on the engine, it is going to run hotter. You are now sending hotter fuel back to the tank. After awhile, you will raise the fuel temperature of the tank to where it will boil. Fuel only needs very low 110ish°F to boil. And higher octane fuels have lower boiling points, so that isn’t helping. Detonatates higher, but boils lower. Anyway, can now boil away in the tank, but still not cause vapor lock like on old carbureted motor due to their pretty well designed pressure regulator and pumps that can still flow boil liquors good enough to never mess with a perfectly running 5.7.

I’ve plopped temp sensors in tank, in line on the send and return lines, and it pretty clear that the 150° fuel returning to the tank is raising the tank temp level. Auxiliary fuel tanks, engine bays loaded with batteries, aftermarket bumpers, skid plates, big tires, roof racks with massive RTTs, it doesn’t matter. This is a deeper problem.

So I feel from my findings building these trucks that, ugh… it pains me to say this.

Toyota F’ed up.

They put so much emphasis on keeping the engine cool, that they forgot about the stuff behind it. Toyota can put in 2 transmission coolers, one engine cooler, steering cooler (which is legit because I broke my Tacoma rack due solely to heat) but they needed to put a cooler for the fuel.

I’m heavy into other Toyota forums from BudBuilt, and the Tundra guys with 5.7s also are plentiful with fuel boiling statements. And if you didn’t know, under those trucks, it’s wide open with space, but they still boil. Because it’s not about crap around the truck, it’s about the motor and fuel system itself.

The 4.0, both single and duel VVT-I and the 3.5 bit have very little reports of boiling fuel. From tuning my own 4.0, how Toyota ran the fuel back to the tank on those, it did not have to cool as much and the way back to the tank. I personally melted a stock resin fuel tank skid on my FJ from exhaust heat. Just melted it like a grilled cheese, but NEVER boiled fuel, or head about anyone boiling fuel then. But have always heard about it from 100 series guys. In Iraq, I ran a lot of 100s and 200s with gas motors (they worked better for our needs than the diesels, that and I blew a lot of turbos and needs more reliability) we boiled fuel all the time. I just had many other things I cared about at the time.

So that’s it guys. Our precious, should be the most perfectly engineered vehicles of all time, is not perfect. Toyota should of managed fuel heat, they didn’t. I have been working on a solution, but honestly, at this point, I’d rather help everyone with knowledge than providing a future solution. We just need to cool the fuel. It’s not hard, it doesn’t hurt reliability (as I know that will be the next thing that most of us won’t be able to accept) it just needs a simple cooler in a good spot. I’ve played with the concept already, and proved that it works. What I haven’t done is made a good kit for it to be plug and play.

So that’s my story guys. On this particulate issue, we need to become Jeep and Land Rover enthusiast, and fix what the factory failed to do in the first place. It’s hard to accept, I’ve personally lost months of sleep over this.

Some extra reading on data points if you want them. I e found that under racing conditions, it’s hard to boil fuel. The reason is because most of the fuel is consumed, and air flow over the top of the motor is high. Remember, there is now factory air flow under the motor, but that’s not the problem, it’s cooling if the top end, and heat rises. High load, and no wind, that builds heat, but uses little fuel, and little cooling from air being literally rammed through the engine bay. Which is off roading or slow towing. LCDC ‘19, I watched two separate 200s with nothing more than all terrain tires boil some serious fuel. I also saw one 200 with a lift and slider boil, and a super built 200 with freaking everything boil. They all did it when off roading. Have air vents won’t help a thing, because heat rises. The air cooling only helps when air is being forced right through the grill over the top of the motor, that it, it has nothing to do with heat down low off differentials or exhaust. I personably have a Jet-Hot coated headers to muffler that cuts radiant heat over 50%. That. It advertised, that real life testing I did. Guess what, didn’t do a damn thing for fuel temps.

Best thing to mirage right now. Don’t ever open your fuel cap, even if you see fuel boiling out. Just like your radiator, pressure raises boiling points. So keep the cap on, unless you like to lower you fuel’s boiling point even lower. Then, turn your engine off. No more fuel running over a hot motor, it then cools very very quickly. Wheeling with people who s*** their 5.7s off a lot seem to never boil. Those who run in low range constantly and leave this motors running when stopping to access the trail, seem to boil much more regularly. Also, as the motor itself gets older, it runs hotter, just how it works, so while I’ve seen more sub 5,000 mile 5.7s boil fuel, it can happen more when they get up there in mileage. Another thing I’ve found it people adding aftermarket wiring to the engine room (the technical term for the fuse box) I’ve seen that play havoc with the fuel delivery and air injection systems cause the motor to run hotter, which as a side affect, boils gas.
 
But why doesnt my HE boil sitting in 115 degrees ambient in Vegas? I've driven that around town in stop and go traffic in 117 degrees and running just standard E10 87 and no fuel boiling or gas smell.
 
But why doesnt my HE boil sitting in 115 degrees ambient in Vegas? I've driven that around town in stop and go traffic in 117 degrees and running just standard E10 87 and no fuel boiling or gas smell.
It’s hit or miss, but I would probably say it’s because you are treating your 200 like a car in that scenario. Stop and go on roads, isn’t what I’ve seen cause the issue. Take it out on trails all day, stay in low range, then let us know. Also, I’m not trying to egg you on, it is a sporadic thing. I’m genuinely trying to help find a solution. That said, we don’t drive air cooled engines. Ambient temps don’t really much to a 200 with how it’s cooled. Then take that stop and go, on that 5.7, is barely taxing that motor. It’s about heavy engine load firstly.

Here is another countless example I have. I was talking with a customer about building his ‘21 HE 3 row. He told me he will be running a trailer and we got to talking about gear ratios. Well, I share a Kimberly Kamper Karavan with my parents who also have a ‘18. They have pulled that thing around western NC mountains and I’ve pulled it many times also. We’ve never boiled fuel. I let him tow it with his stock ‘21 up the mountain to the blue ridge parkway. A 15 mile drive, it’s at 3,000 ft and it was 70° outside. It’s a steep grade up. He boiled fuel, bad, like came out and did a number to the paint work. Needless to say, we then got to talking about the my thoughts on it.

That had nothing to do with altitude, heat, or fuel type. It’s again, engine load with is engine heat.

A fuel cooler is the solution. I even have a good idea how to route it, and we can talk about that in time. I’ve seen these threads go weird too many times, and I wanted to let the community come to grips with the idea that Toyota didn’t do it right before we start talking modifications.

Trust me, over half the work I do to 200s is fixing modifications from other shops, individuals, or dealerships. I’ve tried to keep that under wraps, but I feel it finally needed to be said when it came to this issue.
 
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Geez, You'd think Toyota has to know about this issue. I mean, most of the manufacturers come out to the deserts around Vegas and Laughlin to test under the extreme heat. A friend of mine used to bring new Honda's and Acura's out to test. Ford also tests a lot out here. If my new Cruiser puked fuel out of the cap and damaged the paint, Toyota would be repairing that.
 
Geez, You'd think Toyota has to know about this issue. I mean, most of the manufacturers come out to the deserts around Vegas and Laughlin to test under the extreme heat. A friend of mine used to bring new Honda's and Acura's out to test. Ford also tests a lot out here. If my new Cruiser puked fuel out of the cap and damaged the paint, Toyota would be repairing that.

Of course they must know, but unless Feds force their hand and/or fallout from the issue exceeds the cost of addressing it, any action from them is unlikely.

Maybe few trucks need to go kaboom with people dying (hope not). Might get their attention.

It would be interesting to know where the system is venting from.

As I understand it, the charcoal canister VSV is open to atmosphere when the car runs. Which terminates on a plastic collar around the fuel filler neck. I don't know for sure, but the gas cap likely has a pressure relief threshold. Would it be venting via the charcoal or gas cap. It would be hard to distinguish.

@unclemat - do you have skids? Not sure how much of a problem they are but they likely don't help the situation?

Yep, BB skids.

Why would a HE be any different?

Brand new vs. the 2015 with 73k+ miles now (and only those since 50k are mine).

I’m gonna say something that I’ve been working on for over a year now. It will not be received positively from the community. But please, understand that I’ve been taking measurements across over 80 200s under lot of conditions. It took me a long time to even accept this as I just didn’t feel the failure was what I “wanted to believe.”

Also, don’t take what I say as gospel, I would like to be proved wrong here. It frustrate me a lot on what I believe the issue is.


.....

So I feel from my findings building these trucks that, ugh… it pains me to say this.

Toyota F’ed up.


....

I think you're absolutely right, it's not the fuel. While I'd prefer to see them fess up and pay up for recalling these trucks, this is unlikely (I am still going to file a complaint with NHTSA), I would absolutely love to see a solution from you.

Where do I sign up?
 
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