Eyedaho
SILVER Star
Agreed. I think butane is among the most volatile. I have wondered if higher octane rating gasoline is less prone to boiling, since it's more refined.
Gas tank building excessive pressure & fuel smell. Dangerous for sure! Why does this happen?
- Thread starter 2001LC
- Start date
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I don't know how liquid fuel temp in the rail is meaningless. It should be the single highest temp of the fuel delivery system.
I think if it as one event, from too much temp that effects vaporization and not enough volume or thermal transfer in the tank to end the process. The gradual build up of heat over time at the fuel rail and traveling back to the tank overcomes it's ability to cool it.
After all, if your fuel pump wasn't pushing a few air bubbles the car would start. Never mind the tank venting or gas leaking out the cap or liquid itself. If any fuel comes back to the tank as a vapor, it is pressurizing the tank.
Added heat from other sources matters to. Pump itself, fuel lines close to other heat sources etc.
You're essentially going from 3.5 atmospheres absolute to 1 plus or minus, plus head pressure of the volume in the tank because your return fuel line exits at the bottom of the pump, essentially at the same level of the pick up or sock filter. Plus excess bleed from the regulator and latent pressure from the injector side all the way back to the pump check valve.
Just say for arguments sake that rail pressure leaks down to 21 psi gauge after shutdown within five minutes. (from the FSM)
Various states of tune will dictate how fast it equalizes to zero gauge at the fuel rails.
Worsening the effect with the pressure loss.
During that time temp is going up on the rails from the block. That's easy to measure.
So that combined with the pressure loss on either side of the regulator only increases the likelihood of the pump attempting to push gas bubbles resulting in a hot no start.
There are multiple compression and decompression events happening in the whole travel path. The ones we're worried about are the pressure and temp in the tank and the pressure and temp in the return line. It's just pressure, temp, and volume. One can't change without affecting the other.
All that governs how and why, after it vaporizes/boils.
The process that gets it to that point is someone else's profession. But heat is what makes it happen.
The fuel tank absolutely should be close to ambient. You can see that on a gauge on the supply to the fuel rails. I measure 25-40 degrees F difference at all times above ambient.
For example, driving around all day start and stops, gas station, bank, beer store, UPS etc all day.
Every time I get back in and see liquid rail temp it gets higher and higher at each stop, depending on how long each stop took.
At each start up a 2 or 3 degree drop happens about every 2 seconds or less until it is equal to tank temp. (assumed)
Prolonged driving at low speeds has the same effect as multiple start and stops.
For a year or more this has been a constant. 25-40 above ambient. Driving through a hail storm or a big rain where the temp drops 20 degrees outside you can see this affect the rail temp also. It drops like a rock.
If you take j1000's info also you can surmise that adding an external cooler will keep the delta between rail and tank at 20 degrees F or less.
I wish someone would install a pressure sender on the top fuel tank cover where the connectors are, and a temp sender at the bottom of the tank.
My bet is there is an equalization point and multiple crossovers with temp and pressure. The gas volume expansion is undersold in the tank, greatly. I think this should be obvious to all. I realize the tank is not a fixed container and that some gas escapes, but in this instance where the volume of the gas overcomes the containers ability to vent you might as well consider it to be inflexible.
The shear volume of the tank under pressure and clicking the cap open a few clicks lessoning the ambient pressure inside the tank even just a few PSI will cause a lot more boiling than people think. Desaturation leading to boiling. This is what is happening when liquid and gas vent out your fuel tank.
Personally I haven't had the problem for years. I put in a new pump, walbro at first and then denso stock.
I did add a heat shield, didn't measure anything but it was solved before that with the pump. For me at least.
I don't run the engine cover or the black air train.
I also don't have cats, but that only results in a 100 degree drop at the flange closest to the Y pipe.
I have a pressure sender at one rail and temp sender at the other rail.
I thought this was the most important to keep track of. I have no intention of adding other monitors.
My coolant runs at194-197 F constant. Everything related to that system is new.
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Hmm you guys still chatting endlessly? Well have fun! I'm about to get in my 100 and tow 20 hours without hesitation. Have fun typing!
I just read through this. Do you think this would help with the Vegas heat? Anything new to add since your post from 202? Thanks for the info
Hope this is helpful information for those of you trying to fix this. Most of what you guys talk about is beyond me, so use it if you can and or PM me if you want more formation
2003 LC, 272k miles, owned since 130k, around 10 yrs. all maintaince done at stealership and heavily modified.
just finished up 7 day trip from north Alabama to silverton through Oklahoma City, Albuquerque, Durango and then silverton. As you know these rigs aren’t known for gas mileage and I stopped plenty of times this trip. No issues until I got to Durango with <1/4 tank gas, 81 degrees according to LC. Got to tractor supply and from video you can hear it lightly boiling. See video. No other issues rest of week
Next 7 days are from silverton to SLC and up to Montana. In Thompson spring UT, <1/2 tank of gas, 102 outside and wow was it boiling good! Let it rest for 10 mins and it was still boiling. Took a chance and opened gas cap and stopped boiling within 30 seconds. see video
I do have a scangauge running, water temp if it matters never exceeded 193 entire trip.
2003 LC, 272k miles, owned since 130k, around 10 yrs. all maintaince done at stealership and heavily modified.
just finished up 7 day trip from north Alabama to silverton through Oklahoma City, Albuquerque, Durango and then silverton. As you know these rigs aren’t known for gas mileage and I stopped plenty of times this trip. No issues until I got to Durango with <1/4 tank gas, 81 degrees according to LC. Got to tractor supply and from video you can hear it lightly boiling. See video. No other issues rest of week
Next 7 days are from silverton to SLC and up to Montana. In Thompson spring UT, <1/2 tank of gas, 102 outside and wow was it boiling good! Let it rest for 10 mins and it was still boiling. Took a chance and opened gas cap and stopped boiling within 30 seconds. see video
I do have a scangauge running, water temp if it matters never exceeded 193 entire trip.
James Bentley
SILVER Star
so let me add this to the mix: thumping sound at gas cap
About 85F today and came home from a shopping trip to Sam's and Wally World (both with park/heat soak appx 30-45 min each while shopping).
Once home and while unloading from the back, I heard this thumping faintly as I walked past the Left Rear.
Thought it might be a LR door lock actuator cycling/hung, but confirmed it was not at the LR door.
It was at the gas cap area.
I smelled no fuel/vapors.
Popped the hood and did not hear any similar thumping noise.
Finished unloading (5 min) and still there at the gas cap.
20 min later, no noise.
I have adopted many of the tips/tricks from this thread, but never (yet) experienced the full-on boil or smell or spewing or any driveability issue.
I do fill up until it clicks and then another Gal/buck or so (say 2 more clicks) = it is really full, but not running out the top.
(I haven't yet ordered a LRA replacement tank and I want a full tank dog gone it, lol)
Elevation 564 ft
Coolant temps 190-193 (Scangauge)
I've had the 100 for 2 years and never heard this before (video link above or below)
EDIT:
As I wondered just how full my tank was today, I went out to double-check this evening...Cruising Range = 16 miles!!!
I am on VAPORS!!!
That may explain why I never heard it before as I never let the tank get that low.
Always listen to your vehicles, sometimes they "speak" to you!
Happy Fourth everyone!
About 85F today and came home from a shopping trip to Sam's and Wally World (both with park/heat soak appx 30-45 min each while shopping).
Once home and while unloading from the back, I heard this thumping faintly as I walked past the Left Rear.
Thought it might be a LR door lock actuator cycling/hung, but confirmed it was not at the LR door.
It was at the gas cap area.
I smelled no fuel/vapors.
Popped the hood and did not hear any similar thumping noise.
Finished unloading (5 min) and still there at the gas cap.
20 min later, no noise.
I have adopted many of the tips/tricks from this thread, but never (yet) experienced the full-on boil or smell or spewing or any driveability issue.
I do fill up until it clicks and then another Gal/buck or so (say 2 more clicks) = it is really full, but not running out the top.
(I haven't yet ordered a LRA replacement tank and I want a full tank dog gone it, lol)
Elevation 564 ft
Coolant temps 190-193 (Scangauge)
I've had the 100 for 2 years and never heard this before (video link above or below)
EDIT:
As I wondered just how full my tank was today, I went out to double-check this evening...Cruising Range = 16 miles!!!
I am on VAPORS!!!
That may explain why I never heard it before as I never let the tank get that low.
Always listen to your vehicles, sometimes they "speak" to you!
Happy Fourth everyone!
The valve inside the cap will flutter and vent off excess tank pressure the evap can’t keep up with. Mine does it occasionally.
With your 04, topping off the tank past the first click will eventually saturate your charcoal canister with fuel and kill it- as it resides just below the filler, it’s easy for the overflow to flow right into it. This contributes to evap issues & tank over pressurization.
Early model years with canister in the engine compartment don’t experience the same overfilling problem
With your 04, topping off the tank past the first click will eventually saturate your charcoal canister with fuel and kill it- as it resides just below the filler, it’s easy for the overflow to flow right into it. This contributes to evap issues & tank over pressurization.
Early model years with canister in the engine compartment don’t experience the same overfilling problem
- Thread starter
- #648
I'll assume you mean "pink" which is Supper Long Life (SLL) pre diluted vs "Red" which is Long Life (LL). If you used 100% red, without diluting 50%, it will not cool properly.
Thermostat & cap are easy to test. But also cheap and easy to just replace at 90K service. They do go bad!
Washing radiator fins is helpful. But yes, best is replacing. It depends on how clogged, which depends on environment driven in or even just parked in (flood).
To be clear: I'm speaking about exterior of all three radiators. They get clogged with grasses, cotton, bugs, feathers, mud, etc. I've even seen Styrofoam sheets between them (like in a flood).
More info like OAT, sun mid day, were you climbing hill just before issue, ECT (engine coolant temp) and fuel trims could yield clues. Regularly driving in dusty condition, air filter and radiator fins do get clogged and need service more often.
Additionally; loaded down with gear pulling a load. You'll run hotter.
Once a 100 series actually boils fuel, or a 03- up gas tank is overfilled. We may have created a EVAP issue. i.e damage to charcoal canister or system ability to recirculate.
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Stupid question here and sorry if its an obvious reason but please let me know. What would the harm be in leaving the gas cap a little loose to let it not build up pressure? I know the check engine light will come on but I don't have to get it smogged until March. On these hot Vegas days by 1PM my fuel is boiling and the smell can be overpowering. If its relieving out the gas cap then I don't smell it as much in the cab. Any good answers to my stupid question would be much appreciated. 02 LC 97K Miles.
Any venting or fuel smell is a huge fire risk. The engine bay may be a little more protected from an outside spark risk , but breathing fumes all the time is harmful to you. Do what you got to do. They are all sub optimal choices.
- Thread starter
- #651
I'd not!
You're likely in need of a tune and coolant service. With the 98-02, the charcoal canister or other components of EVAP are not usually damaged, once fuel boiling happens. But they can be, just not common. So start with the basics.
You've low miles. But this doesn't mean radiator fins not clogged by grasses, weeds, cotton, feathers, bugs, mud, etc.
Just because coolant reservoir at max line, doesn't assure radiator and engine block full of coolant. Nor reservoir, thermostat or cap working to spec.
Nor does assure you've no vacuum leaks, sparks are tight in the heads.
Radiator fins need cleaning! Alert Alert Alert
I've a 06LC w/192K I just bought. In reading history I found PO complained of engine temp raising when both front and rear AC on. Toyota Dealership diagnosed with clogged radiator fins. Recommended new OEM radiator, $600 for the US spec Radaitor plus coolant and labor. They should have added...
forum.ih8mud.com
I'll add: I've lost count of the issues I find, after some shop has worked on on rigs. Most mess these up! Even Dealerships!
I'll admit I haven't followed this thread much but for those out there collecting info I have experienced the fuel bubbling issue a few times and again this past weekend.
Facts
- Full tank
- 87 octane
- 90-100 degree outside temps
- Climbed from 2k to 7k feet
- New OEM radiator, thermostat, and cap. Cleaned and properly filled with 50/50 toyota red within the past year.
- All vac lines are functioning properly without any cracks.
- Foam in place on radiator and skid plate
Truck ran great the entire time but once stopped I could hear a funny hissing noise out of the evap system near our fuse box. I felt vibrations on thise one area so pulled the line to vent it and that blew for about 15-20 minutes and smelled like rotten fuel ( similar to when you open up an old nasty carburetor ) I didn't pull the gas cap completely off rather just cracked in and let it vent for about 15-20 minutes as well. Once the hissing stopped I opened the cap and could hear fuel gurgling.
Sick of throwing parts at this truck for stuff that isn't broken yet so I'm just going to ride it out and avoid high heat off roading. Just wanted to share another case of this issue happening to our rigs.
Facts
- Full tank
- 87 octane
- 90-100 degree outside temps
- Climbed from 2k to 7k feet
- New OEM radiator, thermostat, and cap. Cleaned and properly filled with 50/50 toyota red within the past year.
- All vac lines are functioning properly without any cracks.
- Foam in place on radiator and skid plate
Truck ran great the entire time but once stopped I could hear a funny hissing noise out of the evap system near our fuse box. I felt vibrations on thise one area so pulled the line to vent it and that blew for about 15-20 minutes and smelled like rotten fuel ( similar to when you open up an old nasty carburetor ) I didn't pull the gas cap completely off rather just cracked in and let it vent for about 15-20 minutes as well. Once the hissing stopped I opened the cap and could hear fuel gurgling.
Sick of throwing parts at this truck for stuff that isn't broken yet so I'm just going to ride it out and avoid high heat off roading. Just wanted to share another case of this issue happening to our rigs.
I'd not!
You're likely in need of a tune and coolant service. With the 98-02, the charcoal canister or other components of EVAP are not usually damaged, once fuel boiling happens. But they can be, just not common. So start with the basics.
You've low miles. But this doesn't mean radiator fins not clogged by grasses, weeds, cotton, feathers, bugs, mud, etc.
Just because coolant reservoir at max line, doesn't assure radiator and engine block full of coolant. Nor reservoir, thermostat or cap working to spec.
Nor does assure you've no vacuum leaks, sparks are tight in the heads.
Radiator fins need cleaning! Alert Alert Alert
I've a 06LC w/192K I just bought. In reading history I found PO complained of engine temp raising when both front and rear AC on. Toyota Dealership diagnosed with clogged radiator fins. Recommended new OEM radiator, $600 for the US spec Radaitor plus coolant and labor. They should have added...
I'll add: I've lost count of the issues I find, after some shop has worked on on rigs. Most mess these up! Even Dealerships!
The radiator is clean. The rig has never even come close to overheating as far as engine temp per the gage. Never even gone over the center line and is usually if not always a bit below the center for temp. What would a vacuum leak or loose spark plugs do? If it would cause overheating thats not happening. Truck runs great. Only has issues when it gets super hot (115+) in the afternoon then fuel tank starts to get pressurized and smell of gas comes into the cab from the charcoal filter area. I've loosened the gas cap slightly now for a day and so far no smell. I just filled up and its getting to be afternoon so I will check in again later with any updates. Thanks for any imput!!!
My coolant temp seems to be running in this same range. Doesn't really matter what outside temp is. Its always been serviced by a trusted Toyota mechanic. I did hose the radiator as best I could. I think the later models might just run hotter.
I have a question about the charcoal canister - I purchased part number 77740-60440. It said it would fit my 06, but it doesn't really look the same. Can I use it anyway? Is there a specific part number for the later years? I apologize if this is spelled out somewhere else. I haven't been able to find the answer.
Cheers
Just fyi you can't trust the temp gauge in the dash. I was up to nearly 220 on the scanguage and the temp gauge on the dash read the same as it did at 180. The scanguage is even using the computer's sensors for temp. That gauge is useless other than letting you know when the truck is warmed up.
77740-60450 5/2005 and up
partsouq.com
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Rig details at end of post. I'm hoping this information helps others troubleshooting fuel boiling.
Last summer, I went up to Coyote Flats in the Eastern Sierra Nevada's (offroad trail up to 11k elevation) and had gasoline smell and fuel gurgling in the tank and some spilling out of the fill tube. I posted about it previously in the thread. Since then, I done some more PM, but I believe that the issue for this rig is solved.
Last week, July 1, I went up to Coyote Flats again with air temp of about 100 F in the Owens Valley and a full fuel tank of E10 91 octane. It's a steep offroad trail that takes you up to 11k elevation. I drove most of the trail in 4 Low and had no issues with fuel boiling or fuel smell. Air temperature at 11k elevation was about 75 F. During the trip, transmission temp stayed low, about 150 F and Coolant Temp never went over 205 F, usually hovering around 190-195 F. I stopped a few times to check air temperature under the hood and found 140 F to 145 F under the hood. There was definitely heat soak from the slow uphill trail driving.
99 LC, about 260k miles
Cooling related:
Replaced all evap system lines under the hood and replaced the VSV's on original charcoal canister
Amazon reflective fuel line wrap on fuel lines near catalytic converter
New radiator cap, filled with Toyota pink
New radiator at 250k miles, replaced heater T's with OEM
New OEM fuel filler cap
Original fuel pump
Weight related:
Metal tech sliders, Coastal Front bumper, 33" tires, heavy 270 awning up top, carrying 30L of water/extra fuel in jerry cans.
Last summer, I went up to Coyote Flats in the Eastern Sierra Nevada's (offroad trail up to 11k elevation) and had gasoline smell and fuel gurgling in the tank and some spilling out of the fill tube. I posted about it previously in the thread. Since then, I done some more PM, but I believe that the issue for this rig is solved.
Last week, July 1, I went up to Coyote Flats again with air temp of about 100 F in the Owens Valley and a full fuel tank of E10 91 octane. It's a steep offroad trail that takes you up to 11k elevation. I drove most of the trail in 4 Low and had no issues with fuel boiling or fuel smell. Air temperature at 11k elevation was about 75 F. During the trip, transmission temp stayed low, about 150 F and Coolant Temp never went over 205 F, usually hovering around 190-195 F. I stopped a few times to check air temperature under the hood and found 140 F to 145 F under the hood. There was definitely heat soak from the slow uphill trail driving.
99 LC, about 260k miles
Cooling related:
Replaced all evap system lines under the hood and replaced the VSV's on original charcoal canister
Amazon reflective fuel line wrap on fuel lines near catalytic converter
New radiator cap, filled with Toyota pink
New radiator at 250k miles, replaced heater T's with OEM
New OEM fuel filler cap
Original fuel pump
Weight related:
Metal tech sliders, Coastal Front bumper, 33" tires, heavy 270 awning up top, carrying 30L of water/extra fuel in jerry cans.
I have been following this thread for a while now, but are most people that are having this issue coming from lower elevations?
@jerryb - Thanks for that. I booked marked that link. Very helpful.
@archerwolf - I did that route last summer too. No boiling issues for me then. It is amazing up there!! So beautiful. I'm going to try to get back up again this year, hopefully without the boil.
@phatdragon - I don't know about most. For me, it has happened only once. I went from 200ft below sea level to 4000 feet in 10 miles. About 90 degrees outside. Slow, 1st gear 4 wheel drive road but not anything crazy.
@archerwolf - I did that route last summer too. No boiling issues for me then. It is amazing up there!! So beautiful. I'm going to try to get back up again this year, hopefully without the boil.
@phatdragon - I don't know about most. For me, it has happened only once. I went from 200ft below sea level to 4000 feet in 10 miles. About 90 degrees outside. Slow, 1st gear 4 wheel drive road but not anything crazy.