100 Caught fire & gas tank venting concerns

[abuck99]

Yes they are, see @TonyP 's post above. They asked the Toyota rep about it at LCDC 2017 and didn't get much of an answer.

Duh- thanks AF for pointing that out.

Thinking outloud- Ok so fuel vapor pressure not necessarily fixed across series platforms. Which brings me to my next question is this mainly happening on older trucks, or does it happen on new, 1-3yr old-5yr old- 10yr + old trucks. To get to a root cause wether its environmental, or component related or both as the vehicle ages or is it a design issue.

 

[abuck99]

The EVAP system designs updated with changes in EPA mandates- getting far more complicated with the latter version- this is when the charcoal cannister moved from the engine compartment to underneath by the spare tire location.

 

[TonyP]

We only had a couple of '16+ Land Cruisers during this meeting but the components are the same throughout the 200 series'. That being said, the answer is yes, it still occurs in newer models.

 

[GDenver]

Duh- thanks AF for pointing that out.

Thinking outloud- Ok so fuel vapor pressure not necessarily fixed across series platforms. Which brings me to my next question is this mainly happening on older trucks, or does it happen on new, 1-3yr old-5yr old- 10yr + old trucks. To get to a root cause wether its environmental, or component related or both as the vehicle ages or is it a design issue.

I happened to me on my first 1999 LC straight off of the showroom floor. It was a 3 year lease, and I owned it from 0-36k miles. It seems to be a design issue in my opinion. My issues could be worse than others as I am at 5200ft elevation, and it's not uncommon for me to run over 10000ft and back a few times a week. Even so, I have never had this issue with any other car.

 

[PabloCruise]

Our 100s/470s OE gas caps have a one way vacuum valve so makeup air can be drawn into the tank. Have a look in the center of your cap, you can suck air through but can’t blow it back out to atmosphere - if the valve is working as designed.

That is my basic understanding as well - the cap is supposed to allow air to enter under vacuum conditions (night time, when the fuel cools off), but if the tank develops pressure, the pressure is supposed to exit through a valve and move to the charcoal canister where the vapors will eventually be aspirated with air for combustion. So is it the valve on the tank that is causing the pressure to build up to problematic pressures?

 

[Julian Stead]

I am curious to know what the temperature of the gas gets to in the tank, maybe it is a temp issue aswell and not just a pressure issue, as opening the cap alone wouldn't have such a effect(as in make it boil) unless the temperature is raised aswell surely. I wonder what the boiling point is at 10k ft.

 

[1meancruiser]

That is my basic understanding as well - the cap is supposed to allow air to enter under vacuum conditions (night time, when the fuel cools off), but if the tank develops pressure, the pressure is supposed to exit through a valve and move to the charcoal canister where the vapors will eventually be aspirated with air for combustion. So is it the valve on the tank that is causing the pressure to build up to problematic pressures?

My mechanic told me I needed replace the valve inside the tank as well as the charcoal canister. I believe this and/or the older design charcoal canister are the root cause of this problem...my 2 cents.

 

[suprarx7nut]

That is my basic understanding as well - the cap is supposed to allow air to enter under vacuum conditions (night time, when the fuel cools off), but if the tank develops pressure, the pressure is supposed to exit through a valve and move to the charcoal canister where the vapors will eventually be aspirated with air for combustion. So is it the valve on the tank that is causing the pressure to build up to problematic pressures?

I agree with you and this is where I'm lost. I thought the evap system was a simple one way check valve with a break open pressure (is that the right term) of a few PSI. That is plumbed into a valve that controls whether or not the engine is pulling fuel vapor into the intake to combust. If that were true, though, the tank should never be able to build troublesome pressure once the engine is warm enough to introduce the fuel vapor in the intake. Maybe I should read the FSM at home. I bet they explain something there.

The pressurized tank of the 100 series completely puzzles me and makes me think it's more complicated than I think - and I'm not sure why.

 

[Julian Stead]

Maybe the cap isn't designed to work at altitude, the higher you go the less pressure difference between vacuum and atmospheric. Just guessing.

 

[PabloCruise]

I am curious to know what the temperature of the gas gets to in the tank, maybe it is a temp issue aswell and not just a pressure issue, as opening the cap alone wouldn't have such a effect(as in make it boil) unless the temperature is raised aswell surely. I wonder what the boiling point is at 10k ft.

Opening the cap would have the effect of lowering pressure in the tank, and thus allowing the fuel to start boiling. Remember, you can boil water at room temp by pulling a vacuum on it.

 

[PabloCruise]

I agree with you and this is where I'm lost. I thought the evap system was a simple one way check valve with a break open pressure (is that the right term) of a few PSI. That is plumbed into a valve that controls whether or not the engine is pulling fuel vapor into the intake to combust. If that were true, though, the tank should never be able to build troublesome pressure once the engine is warm enough to introduce the fuel vapor in the intake. Maybe I should read the FSM at home. I bet they explain something there.

The pressurized tank of the 100 series completely puzzles me and makes me think it's more complicated than I think - and I'm not sure why.

These systems are complicated. I have an engine swap that I had to figure out - OBD2 engine into OBD1 body & ECU. I studied the FSMs for the vehicles and from '94 to '98 the manufacturer had developed 3 different EVAP systems. That tells me that developing these systems is not cook book formula...

 

[PabloCruise]

I think it would help if people in this thread identify what year their 100/470 is.

'99 470

 

[abuck99]

Its in my sig line

 

[PabloCruise]

Its in my sig line

Mine too, but not everyone is.

Plus, you cannot see the sig line when mobile...

 

[fireball]

Rotate your phone 90 degrees. Sig lines show up when I hold my iPhone sideways.

 

[SARguy]

until this summer I had two 1997s as DD. the LC has always, up to 280k miles when I sold it, had the gas smell, and high pressure hissing when the gas cap was opened. My LX 450 with 275k miles never had a problem. Hot days, high altitude small pressure buildup but not enough to be concerned. I always chalked this up to maybe the PO having replaced the canister, or something.

In July I picked up an 04 LX470 with 110K miles. Everything extremely well maintained. I live at about 5000 ft above sea level. I was shocked the first time I pulled up to fill up to hear my gas boiling. I began to observe it happening after driving whenever it was over about 90 degress. Not only that, but I could visibly see a plume of gas vapor which was escaping from the car, but for 5-6 long, and 1 to 2 feet wide the plume was visible as it distorted the transmission of light.

I have no doubt at all that any spark near such concentrated fumes would be explosive.

I have been careful not to top off, and to make sure the gas cap is fully tightened. I dont know if it is just that it is cooler now, or if it has been not topping off/ tight cap that has helped. I have never had any other car do this at all so I would agree toyota has a long term unsafe design problem here.

 

[Austin Hot Shoe]

Agreed there is a problem, same happened to me with pressure build up while at HIH7....Had to vent w 5/8 full at 12k feet, this was after running for about 2 hours. Had @Skidoo as a witness, very dangerous IMO. THE BIG QUESTION IS WHAT CAN WE DO AS A GROUP TO GET TOYOTA TO HELP. 05 LC, 90k miles.

 

[Skidoo]

There were a number of 100s at HIH, where we were well above 10,000 ft, that I witnessed ( @Austin Hot Shoe was one) cracking the cap and venting for minutes.
It was pretty amazing for how long and how much vapor came out. It is not like a fill up at a station where it takes a few to several seconds to depressurize. There was enough pressure that the cap would get tossed if you quickly unscrewed it.
It took about 3 minutes to safely depressurize my 2000 LC.

Since the fuel injection system bypasses excess fuel back to the tank the temperature of the fuel could be an issue.

 

[LostAfrican]

I'd like to add my experience to this discussion and hopefully help the collective wisdom.
01 LX with 16 gallon gravity fed aux tank (no transfer pump).

(I am going to be brief...its late and I am tired...not being snippy).

The gas cap is most definitely intended to be a one way valve, for letting air in and not vapor out (unfortunately imo).
Charcoal canister in the 01 is up front.

My understanding of the CC operation is as follows:
When engine is not running, vapors vent from the tank to the canister and then through the charcoal to remove the odor and then out into the atmosphere in the left hand frame rail! Follow a hose from the canister to see this.
When the engine is running, vapors vent to the canister and then get sucked into the manifold from the canister due to the low pressure in the air intake manifold. A combination of valves on the canister choose the path to vent.

Pressure builds up in the tank due to altitude changes (up) and even temperature increases. The pressure can't vent through the canister if the canister has been flooded with gas (liquid form). Two things can happen here. Gas (liquid again) carries charcoal fragments through the filters into the valves that operate the venting options for the canister. Or, gas can leave gum/residue on those same valves. The effect is the same, the valves get stuck in the wrong positions. Also having liquid gas in the evap. line from your gas tank to the canister or liquid gas in the canister plug it up - preventing the tank from venting.

Gas can get into the evap line and/or the canister during wheeling if the tank is full-ish, and your cruiser is going up/down hill - very steeply - which interestingly enough happens a lot when you go wheeling....or even driving in the mountains.

In my case, before I realized this...I exacerbated the issue, because of my aux tank set up. The Front Runner aux tank sits above the spare tire in the back....and its gas fill line is higher than the top of the main tank. This means that if the aux tank is full, there is no air gap in the top of the main tank which means its really easy to flood the evap line to the canister and the canister itself! I have since replaced my canister with a cheap one here. I really suspect the FR aux tank is intended for diesel and not petrol...but hey - whatever.

My solution was to move my evap line from the main tank to the top of the filler neck so that its never under the gas fill line of either tank - even on an incline.

Some ideas for trail-only solutions.
When I was debugging my issue, for a while I bypassed my canister completely and hooked the evap line from the tanks directly to the frame rail vent line. Sometimes there was an odor when stationary...but not bad. I will say that the engine seemed to run much better too, it was awesome. So an option for those mountainous trail days is to take along a little fitting and temporarily connect your evap line to the vent line so that you tank can breathe more freely. Yes, you may get a CEL, but it really means nothing and is easy clearled with your *Gauge. I think venting a little like that is low risk, and much lower risk than driving around withe a pressurized tank. ( I have heard mine pop and creak even when under pressure).

Of course you can also not fill up so full so that driving up/down hill doesn't flood your evap line/canister....but for offroad mpg this seriously can reduce your range.

I do think that if your canister has been flooded, even just a few times, it may already be clogged ...

HTH...

 

[savirc]

2001 LC here. You can find a RTH thread here while on my way thru Black Gap in Big Bend. For anyone here saying to let the system purge out, it's one of those things that if it hasn't happened to you its hard to grasp the amount of pressure built up. There is no way the system will manage it. It's overwhelmed at the point of smelling gas inside the cab. It's in my opinion a design flaw regardless of the changes in fuel and Toyota needs to do the right thing. Unfortunately until someone dies and there is a big lawsuit it won't happen. The pressure is so high that it can take over 30 mins for gas to stop rushing out of the cap and sometimes even fuel. It's extremely dangerous and borderline criminal to have no solution for it from Toyota. There has been less dangerous recalls made by other manufacturers. I can't figure out why this one is not getting any attention. Hope this thread works as a reference for someone in the future as proof there is a big flaw that was not taken seriously.