I have a 2006 LC. I have had this issue four times over the years during hot summer all in the same place going from SoCal to Las Vegas…which is a long slow hot climb uphill. Makes sense. Another two times were in 110 degree plus days returning home from Lake Mead which is about a 40 mile drive. I have since replaced all the items mentioned in my post above. I don’t recall having fuel boil in any of those situations so again makes sense. Just this last winter (so temp was maybe 50 degrees) I did a hard trail at altitude above 8000 feet and experienced the fuel boil effect and slowly vented. Another LC with me experienced the boil also. Neither of us stalled though like the four times I experienced above. So again your description sounds accurate for those long hot uphill drives. In Colorado last summer I spent an entire week at altitude but filled tank to 3/4 with ethanol free gas and no boil and no stalling. Thanks for the detail as I now understand the difference between vapor lock and the stalling.
Gas tank building excessive pressure & fuel smell. Dangerous for sure! Why does this happen?
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I've been collecting data focused on ECT of various years. To get a baseline. Any you can add, is appreciated.
I'd be very interested in what your fuel trims and ECT (engine coolant temps) are running. At what MPH, RPM, IAT & OAT. To get sense of driving condition(s). Both just cruising on HWY and when you boil.
I see you've 06 medium built with some aftermarket under-shielding. Were they in at times of boiling. Can you post a picture of you ASFIR front & gear skids?
Are radiator fins clean of mud, dust, grasses, bugs, feathers, etc.. Has coolant system been serviced i.e: thermostat, cap, flushed w/ Toy SLL (pink) and all vacuum leaks stopped?
I found most 100 series running way to hot. In most ever case they need servicing. Once done ECT comes down.
I've also notice the different grouping of years, run different temps ranges. With VVT running highest and widest range.
One exception is my 07, which in mild weather (65F OAT & sunny) is ECT 184 to 187F. Can't wait to try in summer heat.
You can see my detailed breakdown of the mods in this post: Gas tank building excessive pressure & fuel smell. Dangerous for sure! Why does this happen? - https://forum.ih8mud.com/threads/gas-tank-building-excessive-pressure-fuel-smell-dangerous-for-sure-why-does-this-happen.1214321/page-11#post-13251496
Did probably 1000 miles of trails last year in the midst of doing these mods including but not limited to Blackbear Pass, Tincup Pass,
San Rafael Swell, North Hill Sand Dunes, Moab etc. Been up to 12-13k ft regularly. If you've seen my Skydio videos you've seen most of it already. Tried and tested not just posting on the internet.
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Time to start getting some OBD2 readings and maybe see if I can get some IR readings from a temp gun on some components under the hood. My situation is improving, but it finally had too much yesterday on the White Rim Trail (approx. 6kft tops), 98-102F OAT, 4-low, venting w/ smell around lunch time (driving since 7am) and boiling by 2pm.
On the highway, including the climbs out of Green River on I70 in the San Rafael Swell at 103F, zero problems. Minor hissing when removing the cap to fill up and no boiling. I even parked in my garage and no fuel smell. So I only have the issue now in 4-lo at crawling speeds (this is an improvement).
Done so far ('03 LX470, 160k miles)
Ethanol Free Fuel (negligible difference for me).
Filling tank halfway (seems better when tank is full)
Charcoal Canister and intake VSV.
Spark Plugs
Pre-cat O2s
Reflective tape on the front of the tank skid and near the exhaust
Complete cooling overhaul during timing belt swap (10k miles ago): Hoses, t-stat, water pump, fang clutch, radiator, radiator cap, gas cap, etc.)
Plan of attack: Drive a bit and get some OBD2 readings. Then probably fuel pump, extend the cat heat shield, and wrap engine bay fuel lines.
If that doesn't fix it, it might be time to entertain other options. As much as I love my LX, if it's going to spew gas on every adventure over 88F, it's not the desert 4wd for me.
On the highway, including the climbs out of Green River on I70 in the San Rafael Swell at 103F, zero problems. Minor hissing when removing the cap to fill up and no boiling. I even parked in my garage and no fuel smell. So I only have the issue now in 4-lo at crawling speeds (this is an improvement).
Done so far ('03 LX470, 160k miles)
Ethanol Free Fuel (negligible difference for me).
Filling tank halfway (seems better when tank is full)
Charcoal Canister and intake VSV.
Spark Plugs
Pre-cat O2s
Reflective tape on the front of the tank skid and near the exhaust
Complete cooling overhaul during timing belt swap (10k miles ago): Hoses, t-stat, water pump, fang clutch, radiator, radiator cap, gas cap, etc.)
Plan of attack: Drive a bit and get some OBD2 readings. Then probably fuel pump, extend the cat heat shield, and wrap engine bay fuel lines.
If that doesn't fix it, it might be time to entertain other options. As much as I love my LX, if it's going to spew gas on every adventure over 88F, it's not the desert 4wd for me.
You've done basically every fix I've been considering.
My story started last year when i started towing in summer in high heat and high altitude, but it extended to normal driving in the high temps. Happened over memorial day on cinnamon pass(12k+ ft) just 4 wheeling with low ambient temps. That was with ethanol free gas too. I think the elevation plays a big role one the boiling aspect.
But this trip that I'm currently on, I'm not having as much issue despite the towing of a 6k lb trailer. I finally bought a scanguage and am doing a lot to control engine temps and trans temps and keeping the engine load relatively low. I've had much less boiling, but it still happens at altitude after a big grade. But i haven't taken any other steps to control it yet besides maintaining my cooling system and occasionally E0 gas
My 2006 just left us stranded (again) at barely over 11k feet yesterday from vapor lock. I've wrapped fuel lines, unwrapped them (didn't seem to change anything), changed filters, put in a new OE fuel pump, and of course run E0 as often as possible.
I'm so done and nearly out and ready to sell this 100. I can no longer rely on it to get me and my family home. Not even my fuel-boiling 80 continually stranded me like this.
I'm so done and nearly out and ready to sell this 100. I can no longer rely on it to get me and my family home. Not even my fuel-boiling 80 continually stranded me like this.
Mine has done it at all elevations, only constant is heat.
geez that's the first time I've heard about full on vapor lock
Do we know if this happens to 4.7 Tundras as well?
High hot and heavy. I was not heavy and ambient was maybe 60F. Elevation, observationally, is my only constant.
What's does stranded entail? My 06 has this problem pretty regularly, but I usually just have to wait 20 or so min and it starts right up. Are you saying it totally died and had to be towed out?
Have you done a cooling system overhaul? Do you hear exhaust more than you should in the wheel wells? I suspect excess engine heat may be a contributor and something otherwise worthwhile to overhaul. Radiator clean,
Wondering the same. My 06 has an annoying long start when hot. It's only failed to start a couple times and fired up again soon after. Dead for 20 mins is annoying, but not stranded. Dead for much more and I can understand wanting to sell it.
anyone wonder how that two terminal wire jumper that runs from the top of the tank penetrator is standing up to time? The one that goes to the pump? (LC pump harness # is 777850-C020 )
I know mine looked pretty bad when I had it out the first time.
I still question voltage drop and resistor interference in the pump circuit affecting flow rate.
I'd sure wire up a battery +volts set up to the pump itself with a switch before I sold the thing.
Or ask someone smarter if higher volume flow from back to front would help or hurt the heat transfer situation.
I know mine looked pretty bad when I had it out the first time.
I still question voltage drop and resistor interference in the pump circuit affecting flow rate.
I'd sure wire up a battery +volts set up to the pump itself with a switch before I sold the thing.
Or ask someone smarter if higher volume flow from back to front would help or hurt the heat transfer situation.
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My 07 rocks always starts up immediately and fuel no longer boils. Sorry you didn't follow my tips.
There are two things that affect liquids boiling; heat and atmospheric pressure (elevation).
Heat is obvious. Atmospheric pressure is two fold; first does your tank maintain pressure or does it leak? If it leaks then the pressure inside your tank will be at atmospheric pressure. If you are at high elevation your tank's pressure is also at high elevation = easier to boil. If your tank doesn't leak then the pressure increases with heat = impossible to boil.
Everyone who has boiling fuel has a leaking gas tank, fact.
Here is a sensor and gauge to monitor your fuel temperature: https://www.amazon.com/dp/B071JCCWGF/?tag=ihco-20
There are two things that affect liquids boiling; heat and atmospheric pressure (elevation).
Heat is obvious. Atmospheric pressure is two fold; first does your tank maintain pressure or does it leak? If it leaks then the pressure inside your tank will be at atmospheric pressure. If you are at high elevation your tank's pressure is also at high elevation = easier to boil. If your tank doesn't leak then the pressure increases with heat = impossible to boil.
Everyone who has boiling fuel has a leaking gas tank, fact.
Here is a sensor and gauge to monitor your fuel temperature: https://www.amazon.com/dp/B071JCCWGF/?tag=ihco-20
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I'll buy it, if/when your ready to sell. I Love the color!
All fuel boiling issues are correctable IMHO. It just a matter of finding and correcting. In a pure stock rig running under maximum weight limits, wrapping and shielding should not be necessary. In a built rig, it may be necessary.
IMHO, they don't come from factory boiling fuel, but condition(s) develop over time that lead to fuel boiling.
Number one from not being maintained properly. First and foremost is coolant system PM. Second, is must be tuned well. Which naturally includes, no vacuum leaks. Third, all gear boxes, transmission and engine oil need to be in good condition.
Low Fuel pressure or delivery, can cause the 4.7 to run lean/hot. This can be issue(s) from fuel pump to fuel injector and any component in-between, any or combination that can reduce injector flow rate. The 06-07, which has a different fuel pump then it's predecessors, has it's own issues. This fuel pump (smaller) delivers less fuel/pressure when hot if defective. My theory is, the resistance goes up in wiring and motor, as temperature raises. This reduces pump speed, as such, pressure in fuel system drops to low (lean). Pump will pressure test fine, in the shop, but fail in the field. Recognizing signs of weak pump, is only way I have found bad pumps. As @jerryb "question": "voltage drop and resistor interference in the pump circuit affecting flow rate" I also find a lot of battery issues from oxidation on post & clamps and into wires under sheathing. This too increases resistance, to all motors!
Built and modified rigs have some additional issue to consider. Weight has some effect, and modified fuel systems has a lot of effect. Number one issue, IMHO, is blockage of air flow. Blockage of air flow and trapping hot air I feel is number one considerations of a non stock 100 series. To a lessor extent, is more mass under the hood retaining heat. i.e larger batteries, pumps, additional wiring, etc.
1) Blockage in front of radiator reducing air flow though fins, along with iron mass (bumper & winch) retaining & transferring heat.
2) Air flow around exhaust headers and CATs, trapping heat around fuel lines and directing heat onto fuel tank, I feel is number one issue.
I also suspect once fuel has boiled, we may have damaged the EVAP system. But for some reason we do not get a EVAP DTC. One issue may be from charcoal canister damage, leading to charcoal getting out of it into system piping and valves.
This summer I hope to find out, if belly pan is a big contributor and if EVAP system is getting damaged.
Yawn. Here we go again.
to clarify, the leak could be anywhere in the fuel / evap system - not just the tank right?
for example could be the valve to the charcoal canister?
Yes, any of the lines to of from the fuel tank can leak. Or the gas cap itself.
Fair question. Had to wait until sunset, rest of the parties carried forward and my son in his 100 stayed behind with us (he had zero problems). My other 20 minute waits in the past are more like 45 minutes to cool down sufficiently to start, but this one was many hours. The only thing to which I can attribute this is that the boiling and vaporization temperatures reached did a true old-school-style vapor lock somewhere low in the system. When do our fuel pumps start pumping during start procedures? Not sure if being able to manually enable the fuel bump could preemptively start circulating fuel through the system for a minute or two prior to start?
The question is WHY are so many of us finding and correcting boiling issues? My 100 in question minus 255s and mild OME lift is near stock, and maintained. This happens to me in heat, or when light towing, or just driving around at altitude.
The only logical answer is that Toyota did not truly nor fully field test the UZJ100 (especially later models). Design assumptions were made and production run.
I fully, totally respect you and your knowledge base exceeds mine by miles, but I have to disagree: your statement is just too general. There are terribly-maintained vehicles that don't have this problem. Crappy old Jeeps, GMs, Fords run circles around many of us when this occurs. A Jeeper with more accessories and loaded down ridiculousness than I've ever seen kept circling back to us and asking if we needed help and laughing the entire time.
Super-over-built 60s, 80s, and early-model 100s with fuel boiling and squirting out the fuel door don't have this problem. Somewhere, somehow Toyota missed something in these late-model 100s.
Quite literally brand-new OE pump. December 2020 Toyota battery and I've never had any oxidation. 2yo OE radiator for preemptive maintenance. Admittedly, I've not run AC impedance nor DC resistance on the fuel electrical wires, but I mean we are all supposed to go through wiring resistance tests on Land Cruisers to have a level of confidence with the vehicle?
I removed my fuel line wrapping because I felt it was actually causing subsequent-start issues by trapping (insulating) heat in the lines during shorter stops causing many restart problems for me.
Why Toyota removed the electric pusher fan is beyond me. Oh and BTW all of my scenarios are sans AC running.
I maintain that this is a true design flaw.