Gas tank building excessive pressure & fuel smell. Dangerous for sure! Why does this happen?
- Thread starter 2001LC
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Local temps yesterday hit 103, called it early because of another boiling fuel no hot start issue. Temps are cooler today so hopefully can crack out the last 933 miles. We are in the SD rolling hills right now.
I ordered heat sleeving for the lines and second skin heat shield for the gas tank. I think my issue began when I filled up and immediately hit a high trail in the middle of the day, we smelled fuel when we got to camp. I am guessing that at 160k miles my CC may be done after that.
I am also going to order one of the Innovative Motorsports fuel temp / ethanol content monitors, just need to decide which one and where to install it. I have a new fan clutch at home, probably will change all of that out a little early for piece of mind.
I ordered heat sleeving for the lines and second skin heat shield for the gas tank. I think my issue began when I filled up and immediately hit a high trail in the middle of the day, we smelled fuel when we got to camp. I am guessing that at 160k miles my CC may be done after that.
I am also going to order one of the Innovative Motorsports fuel temp / ethanol content monitors, just need to decide which one and where to install it. I have a new fan clutch at home, probably will change all of that out a little early for piece of mind.
No worries, I’m a bit aggravated and need to get home. If I were solo I would be much calmer.
Just FYI: I have 3 skidplates, front from Slee and 2 from Dissent. I found the plastic sheath had melted in a few places on the transmission wiring. So I cut some holes in the back two plates to let heat from the cats out better. Don't know if the Slee plates are better ventilated.
Thanks for sharing this info. Trapped heat is a problem as far as I can see. Ventilation holes of the OEM metal plate is important. Most skid plates are plain sheet metal
I have the complete Slee steel set, I have a hard time believing that they didn’t account for proper ventilation, but I guess stranger things have happened. I’ll be spending some time inspecting everything after I get home, and after it cools off. 
This isn’t the first time I’ve done 5k+ mile trips with this setup, never an issue before. I did the entire ID and WY BDRs with nothing like this happening.
This isn’t the first time I’ve done 5k+ mile trips with this setup, never an issue before. I did the entire ID and WY BDRs with nothing like this happening.
Sounds like a plan. I was pretty surprised by how hot is was getting under there after adding the plates. Lots for a 3rd party to balance in plate design between protection and cooling for widely modified rigs. Also thanks to 2001LC for his first few posts in this thread on what he has done to address the issue.I have the complete Slee steel set, I have a hard time believing that they didn’t account for proper ventilation, but I guess stranger things have happened. I’ll be spending some time inspecting everything after I get home, and after it cools off.
This isn’t the first time I’ve done 5k+ mile trips with this setup, never an issue before. I did the entire ID and WY BDRs with nothing like this happening.
GTV
SILVER Star
I never had an issue until I replaced my tank with the LRA 40g. Fuel boiling in summer at high altitude is now a thing. EVAP codes thrown. Considering how close the tank is to the exhaust I shouldn't be surprised. It will undergo heat shielding ASAP and, fingers crossed, that solves the EVAP issue. My theory is the fuel boiling creates a lot more vapor than the canister can handle and it pops a code.
High ambient temperatures, the fact that fluids boil at lower temperatures at higher elevation (could octane play a factor in that?), and that high elevation air is less dense and offers less cooling ability all adds up.
High ambient temperatures, the fact that fluids boil at lower temperatures at higher elevation (could octane play a factor in that?), and that high elevation air is less dense and offers less cooling ability all adds up.
FWIW, have said it here already itt, but I ran ethanol-free gas in my LRA tank with no positive impact.
On the boiling issue or evap?
I’ve never witnessed gas coming back up and out of my tank. But I’m fairly certain I’ve experienced boiling, along with excessive venting and fuel smells in the cabin and around the rear outside.
Ethanol or no-ethanol … hasn’t made a difference on either 100 I’ve owned.
I know that’s anecdotal but it is all I’ve got… along with a 40 gallon tank.
No as it’s not an issue unique to the mod. Happens to stock vehicles too. In fact, I got the LRA on my first 100 as one component in a larger effort to address the excessive fuel smells we’d get from time to time.
While it didn’t fix the problem, I can’t overstate how much more “livable” the 100 is with the added fuel capacity. So much so I swapped it over to my current LX.
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I can't speak for 100 series, that have been modified with LRA. As this does through a bit of a monkey wrench in the mix. It "may" need more venting, than stock EVAP provides, IDK. A fluid engineer, may be able to answer. My guess is, it does.
For that matter. I can't speak for any 100 series that has had much of any part of fuel, air/fuel mixture, EVAP systems modified or component of any part pollution system.
But here's what I can say, specific to the Unicom. Which came to me, from low altitude (TX & GA) with blown engine at 127K mile, ~8 years ago:
________________________More general to all 100 series.
Why do the charcoal canister become saturated.
Why do off-road vehicle see fuel boiling issues, more often. Take in considerate above. Also engine and AT running hotter. High RPM, pulling more load at lower speeds. Radiators, engine, AT and exhaust. All then have less air flow around them, to carry heat away. In many build rigs, they've under armor, retaining and holding in heat in a tunnel. A tunnel fuel lines are in and ends at fuel tank, dumping heat onto tank. Even those iron bumpers, hold more heat and block air flow.
High altitude, reduce temperature at which fuel boils.
So it not usually just one thing. We start correcting issues up-stream at front of vehicle work our way back, and stop doing things damaging. Then we replace the CC. CC is the most common cause, and is common to all 03-07, that have boiled fuel. A one and done!
For that matter. I can't speak for any 100 series that has had much of any part of fuel, air/fuel mixture, EVAP systems modified or component of any part pollution system.
But here's what I can say, specific to the Unicom. Which came to me, from low altitude (TX & GA) with blown engine at 127K mile, ~8 years ago:
- Clue where at 127K miles. It's engine ran very hot, likely for about 20K miles over ~18 mo. period, prior to blowing its engine from overheating. Due to clogged radiator fins and low coolant level.
- Than at 127K, engine severely over-heated. Worst I've every seen before and since.
- The gas fill area door was bent. Likely, from blow-out of gas cap. At the time I did recognize as such.
- The gas fill area around gas cap and door. looked very mucky. At the time I did recognize as fuel boiling and a Charcoal Canister (CC) issue.
________________________More general to all 100 series.
Why do the charcoal canister become saturated.
- Miles/time. They are a service item. They can last perhaps ~1 million miles or more, in ideal conditions.
- CC life is greatly reduce. If any raw fuel enters the CC.
- Quality of fuel, plays a roll. Some fuel produce dirty vapor. Some produce more vapor. Some boil at lower temp.
- Fuel itself, building up excessive heat. Increase vapor which load on CC.
- Over filling gas tank in the 03-07 is number one caused. How, 1) squeezing gas pump handle after auto shut off (topping).
- Heat expansion. By filling tank on a hot day sunny day. Then parking over a hot ground. Without driving to burn off same gas.
- Filling tank, then ascending steep hill/pass. More so ascending rocky road which on a hot day. Not only slashing into CC, but fluid friction increasing from slashing creates heat (volume, heat expansion).
- Engine running hot, heating return fuel. Compounded on a hot day where fuel lines and tank are also contributing to fuels heat.
Why do off-road vehicle see fuel boiling issues, more often. Take in considerate above. Also engine and AT running hotter. High RPM, pulling more load at lower speeds. Radiators, engine, AT and exhaust. All then have less air flow around them, to carry heat away. In many build rigs, they've under armor, retaining and holding in heat in a tunnel. A tunnel fuel lines are in and ends at fuel tank, dumping heat onto tank. Even those iron bumpers, hold more heat and block air flow.
High altitude, reduce temperature at which fuel boils.
So it not usually just one thing. We start correcting issues up-stream at front of vehicle work our way back, and stop doing things damaging. Then we replace the CC. CC is the most common cause, and is common to all 03-07, that have boiled fuel. A one and done!
2001lc: a very well pressented hypothesis. Not sure how anyone can dispute the logic. This should be pinned.
Toyota Engg in their "send it" (no one will ever know) wisdom, placed the CC LOWER and IN BACK OF the fuel tank too from 03+. On a hill, the CC is bloody below the fuel level and lines. Add in folks who run ethanol + high-test fuel at altitude and this is just a recipe for gasoline disaster.
I've never overfilled my 06's tank, nor did the PO who was my father and also knew better. I run low-test, E0 (exhibits worse if not) when going to altitude or high passes, and I still regularly get the boil, stall, and no restart issue. We can't just fanboi our way out of this. Even if everyone of us overfilled our tanks, this is still a Toyota issue. The clearly non-tested CC placement, EVAP sensitivity, and heat generation is non-comprehensive testing by Toyota. Emissions suck for sure, I'll guess that the emissions compliance were the 11th hour, but other manufacturers don't have this problem. What a brilliant vehicle; the 2UZ is even quite good considering it is a V and a gasser, but this was a miss on the Toyota Engg group.
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