Gas tank building excessive pressure & fuel smell. Dangerous for sure! Why does this happen?

[J1000]

Neat! Any idea what might have been the fix for getting a small bit of pressure in the tank on your rig?

My only guess is heat and gasoline swelling seals or otherwise helping slow the leak. I should have noted that only on the hottest and highest climbs did I have tank pressure, in town or after descents there was no pressure. Even after 5 hours on the highway. So the leak still persists.

 

[suprarx7nut]

My only guess is heat and gasoline swelling seals or otherwise helping slow the leak. I should have noted that only on the hottest and highest climbs did I have tank pressure, in town or after descents there was no pressure. Even after 5 hours on the highway. So the leak still persists.

Alright. I wonder how much pressure is "supposed" to be in the tank. If the purge pulls enough air through the EVAP system, I guess the tank might be intentionally almost zero pressure. Maybe a little pressure at altitude is the first sign of the EVAP system being overwhelmed.... or maybe like you say it's a seal swelling with temp/pressure and behaving more as intended.

The FSMs for the 100 (both my 99 and the 06) are a little lacking in functional explanations. My manuals for the mk3 Supras in the late 80's early 90's have pages of explanations on how the systems work before showing what steps to take in diagnosis. The 100 manuals just step through test steps with no explanation at all on anything. Perhaps that's one of the downfalls of advanced diagnostics being on board - no need to tell the tech how it works, just follow these steps/codes.

 

[kgrove]

Post history does Phoenix

Phoenix indeed. Normal high temps in July and August are probably 108F, but we get a number of days over 115F every year and every couple years go over 120F. I have no idea how hot it gets at radiator height over the asphalt. I know the asphalt itself can get hot enough to soften and deform (I've even seen women's high heel shoes leave imprints), so it's got to be pushing 150F over the road where the cooling system is attempting to do it's work.

I don't have any tools or measurements to record my ECT or I'd gladly cough them up as I know I'm operating under pretty severe conditions a couple months a year that would be a good testing ground to identify problems and solutions.

I only threw out my data point as I found it interesting and potentially instructive that only 6-8 degrees F in OAT can spell the difference between horrible fuel smell and no fuel smell at all. I do think there is something to the Land Cruiser that makes it more vulnerable as my wife's Sequoia with the same 4.7L engine did not have that same problem. Lighter weight car? Different evap system? All three of my LCs (my just aquired '02, my previous '07, and my first one an '06 - all 100% stock and no extra weight) had the fuel problem at least occasionally on super hot days.

 

[d4nvu]

Just came back from a trip up to Mendocino (6800') with my 2002 LX470. I was running California 87 Gas with about half tank starting at the trail head.

Replaced this in the last month:

• Radiator (Spectra)
• Radiator Cap (OEM)
• Thermostat (OEM)
• Coolant Flush (Toyota Red)
• Clutch Fan (Aisin)
• Fuel Pressure Regulator (OEM)
• Fuel Pump (Denso)
• Fuel Cap (OEM)

Still having fuel boiling issues during the climb up. Weather was around 90-95F. Coolant temps were around a constant 184C on the freeway. Trailhead and up - temp climbed to around 190C-204C the highest and had to vent half way through and let it cool down for safety precaution. I have never had a vapor lock issue where it did not start back up. Stayed a night, and went home (downhill) with no problems.

Just a little quick back story- my truck was basically stock before (tires, sliders, roof rack, RTT) and I never had these issues before. A few months back, had a freak accident coming home around 8PM from a snow trip- a piece of metal flew under my truck on the freeway rupturing my transmission pan and fuel tank and everything leaked out. Had the truck towed to Valley Hybrids and it parked overnight outside the shop as they were closed. Got a call from Georg the next day saying it looked a lot worse than it actually was, but had bad news that the friendly local thieves stole both cats under my truck, just my luck right? While they had my truck, they replaced the transmission pan, fuel tank/skid(used OEM), and welded on new aftermarket cats. The car drove fine after getting it out of the shop, but I did not make any trips to high elevation trails. Fast forward a few months later, I added a LOT of weight (front/rear bumpers, dual swing outs, drawers, 12k winch, full skids) and starting making making trips to higher elevations and started experiencing this problem for the first time. I'm still thinking it's a combination of weight and non-OEM cats. I'm going to try heatshielding my fuel lines underneath near the cats as it seems like one of the last things I did not change when compared to @guardcompany.

Did the people who wrapped their fuel lines with tubing sufficient or did you think bending aluminum help as well? Will report back when if I see a change on my next trip.

 

[molonlabemike]

Just came back from a trip up to Mendocino (6800') with my 2002 LX470. I was running California 87 Gas with about half tank starting at the trail head.

Replaced this in the last month:

• Radiator (Spectra)
• Radiator Cap (OEM)
• Thermostat (OEM)
• Coolant Flush (Toyota Red)
• Clutch Fan (Aisin)
• Fuel Pressure Regulator (OEM)
• Fuel Pump (Denso)
• Fuel Cap (OEM)

Still having fuel boiling issues during the climb up. Weather was around 90-95F. Coolant temps were around a constant 184C on the freeway. Trailhead and up - temp climbed to around 190C-204C the highest and had to vent half way through and let it cool down for safety precaution. I have never had a vapor lock issue where it did not start back up. Stayed a night, and went home (downhill) with no problems.

Just a little quick back story- my truck was basically stock before (tires, sliders, roof rack, RTT) and I never had these issues before. A few months back, had a freak accident coming home around 8PM from a snow trip- a piece of metal flew under my truck on the freeway rupturing my transmission pan and fuel tank and everything leaked out. Had the truck towed to Valley Hybrids and it parked overnight outside the shop as they were closed. Got a call from Georg the next day saying it looked a lot worse than it actually was, but had bad news that the friendly local thieves stole both cats under my truck, just my luck right? While they had my truck, they replaced the transmission pan, fuel tank/skid(used OEM), and welded on new aftermarket cats. The car drove fine after getting it out of the shop, but I did not make any trips to high elevation trails. Fast forward a few months later, I added a LOT of weight (front/rear bumpers, dual swing outs, drawers, 12k winch, full skids) and starting making making trips to higher elevations and started experiencing this problem for the first time. I'm still thinking it's a combination of weight and non-OEM cats. I'm going to try heatshielding my fuel lines underneath near the cats as it seems like one of the last things I did not change when compared to @guardcompany.

Did the people who wrapped their fuel lines with tubing sufficient or did you think bending aluminum help as well? Will report back when if I see a change on my next trip.

I think you’re on the right track by shielding the fuel lines. When putting my rock lights under the LX I was shocked by how close the lines where to the cats.

 

[2001LC]

Just came back from a trip up to Mendocino (6800') with my 2002 LX470. I was running California 87 Gas with about half tank starting at the trail head.

Replaced this in the last month:

• Radiator (Spectra)
• Radiator Cap (OEM)
• Thermostat (OEM)
• Coolant Flush (Toyota Red)
• Clutch Fan (Aisin)
• Fuel Pressure Regulator (OEM)
• Fuel Pump (Denso)
• Fuel Cap (OEM)

Still having fuel boiling issues during the climb up. Weather was around 90-95F. Coolant temps were around a constant 184C on the freeway. Trailhead and up - temp climbed to around 190C-204C the highest and had to vent half way through and let it cool down for safety precaution. I have never had a vapor lock issue where it did not start back up. Stayed a night, and went home (downhill) with no problems.

Just a little quick back story- my truck was basically stock before (tires, sliders, roof rack, RTT) and I never had these issues before. A few months back, had a freak accident coming home around 8PM from a snow trip- a piece of metal flew under my truck on the freeway rupturing my transmission pan and fuel tank and everything leaked out. Had the truck towed to Valley Hybrids and it parked overnight outside the shop as they were closed. Got a call from Georg the next day saying it looked a lot worse than it actually was, but had bad news that the friendly local thieves stole both cats under my truck, just my luck right? While they had my truck, they replaced the transmission pan, fuel tank/skid(used OEM), and welded on new aftermarket cats. The car drove fine after getting it out of the shop, but I did not make any trips to high elevation trails. Fast forward a few months later, I added a LOT of weight (front/rear bumpers, dual swing outs, drawers, 12k winch, full skids) and starting making making trips to higher elevations and started experiencing this problem for the first time. I'm still thinking it's a combination of weight and non-OEM cats. I'm going to try heatshielding my fuel lines underneath near the cats as it seems like one of the last things I did not change when compared to @guardcompany.

Did the people who wrapped their fuel lines with tubing sufficient or did you think bending aluminum help as well? Will report back when if I see a change on my next trip.

I agree shield are a must. The non OEM CAT without shield can really put out some heat.
Did you wash your trans oil and A/C (condenser) radiators and replace the foam around coolant radiator?

 

[d4nvu]

I agree shield are a must. The non OEM CAT without shield can really put out some heat.
Did you wash your trans oil and A/C (condenser) radiators and replace the foam around coolant radiator?

Thanks, I used the foam from the original radiator and just sprayed the trans oil and A/C condenser with water.

 

[2001LC]

Thanks, I used the foam from the original radiator and just sprayed the trans oil and A/C condenser with water.

Seems you're staying on top of it. Be interesting to see if installing shields, drops ECT any. One thing I've been considering is a loop effect (as I named it). Whereas the CATS heat the fuel and fuel expand causing engine to run lean, as such, cylinder head temp to rise. ECU works to correct lean condition, but may still run on lean side a bit..

Make sure engine well tuned, and coolant in radiator is indeed to the top.
Watch the transmission temp also. Not shifting into low gears on slow climbs, can spike trans temp more than if in L. This too can affect ECT.

 

[2001LC]

I have the 07 LX that @2001LC has been looking at...

I've had the fuel boiling issue for awhile, happens regularly when offroading in summer time. But have also noticed it on longer road trips in summer, and occasionally around town on hot days in the Denver area. I'll smell gas and see traces of fuel that has come out the cap.. but been around cruisers long enough that I've just accepted it

Few weeks ago had a big fuel boiling issue and a "no start" at China Wall, first time with the "no start" problem and with stream of gas pouring out, so that prompted me to start looking at this deeper. It was probably around 80 OAT and 8500 FT and full tank. We stopped on the trail for a few minutes to discuss route, then I needed my keys to unlock my drawer so shut it down for a few. Restarted, ran very rough and was able to drive for a hundred feet then it died and would not restart. I opened the hood and gas cap to vent, fuel was boiling out for a good 15 minutes. Was able to restart and continue on after 30 minutes or so.

Since starting working with @2001LC, been monitoring engine temps via a ScanGauge after new thermostat, coolant flush, radiator clean out, etc.
On highway and around town, range is generally 190 - 200, usually hovers around 191-195.
After the coolant flush I did drive around that night with both heaters on, 80 OAT and engine temps were between 191-197, coolant level was fine in radiator the next morning.

Also done a couple of trails since:
- Devil's Canyon by Idaho Springs: 66 OAT, 9700 - 10,400 FT, 1/2 tank. No gas smell at start of trail, but definitely once on the trail I could start to smell gas and feel some venting out the cap. On the trail engine temps were pretty steady at 191.
- Pierson Park by Estes Park: 55 OAT, 8600 - 9500 FT, Full tank. Engine temp pretty steady at 190. No gas smell, but was much cooler outside with rain.

We still need to replace fan clutch and radiator cap (was on backorder). Will likely do fuel pump as well.

So we installed new fan clutch along with servicing the coolant system. Dan noted: he could hear coolant fan during HWY driving, after new fan clutch installed, which seems unusual?

Temp are not coming down. They did seem to jump up faster and a little higher before service, during my short test drives, but that's subjective and minor. The radiator support still feels very hot? I'm more an more wondering if we've a bad radiator, but without any outward signs.

Dan experienced crank no start after heat soak (fuel boiling) a few times before and after coolant system service. The 06-07 100 series, are known for having fuel pump issue when hot. So we did a fuel pump & filter R&R yesterday. I'm hopeful that will fix the hot not start condition. But doubt will aid in seeing better ECT. Although we may, if pump was causing a lean running condition.

Found something interesting. Water or what seems to be water came out of fuel pump. Looked like bubble in the fuel as it came out of fuel pump. This may be bad gas. It may be from condensation due to fuel tank excessively heating.

It looked like bubbles in fuel from pump, as I pulled from cage.

As fuel absorbed into paper and evaporated, the bubble remained for a while before evaporating.
I took a cotton Q-tip swab and soak up some of the remaining liquid )bubbles). Than I tried to burn. It did not catch on fire. Seems to be water.

Another interesting thing I saw, was return surpressor niple off lying in bottom of gas tank. This nipple fit on return line at base of pump assembly. I may have knock off, but I'm gentle when snaking fuel pump assembly out of fuel tank. It may have blown off from excessive return pressure/volume. Water in fuel system is damaging to fuel pressure regulator needle. I suppose excessive return fuel pressure/volume could have cause this also. Regardless we going to replace FRP. With age, miles and water in fuel system FPR it's due to be R&R..

But next will be to see if any effects from fuel pump R&R. Than we'll install new OEM radiator cap. Followed by FPR. We're gone one by one to measure effects if any.

 

[2001LC]

 

[d4nvu]

Seems you're staying on top of it. Be interesting to see if installing shields, drops ECT any. One thing I've been considering is a loop effect (as I named it). Whereas the CATS heat the fuel and fuel expand causing engine to run lean, as such, cylinder head temp to rise. ECU works to correct lean condition, but may still run on lean side a bit..

Make sure engine well tuned, and coolant in radiator is indeed to the top.
Watch the transmission temp also. Not shifting into low gears on slow climbs, can spike trans temp more than if in L. This too can affect ECT.

Yup, slow crawls in 4LO and in L just to keep the engine working less. I actually have not tried to check Transmission temp on my scangauge (don't know the code) yet, but will try that next. I'm really hoping the DIY heat shield will help with this problem. The after market CAT is a takeout box shape while the OEM is round, so I'm wondering if the fins of the aftermarket just bring it closer to the fuel lines. I will need to remove the skids to completely confirm. Will report back soon.

 

[Whoareu2200]

My driver side cat is starting to make noise went under and its an aftermarket. Thinking of getting the Magnaflow cats im in California 250 each.

 

[ntk]

I seem to be having similar issues that are described in this thread. I have not witnessed gas spill out of the tank or heard it boiling, but I have noticed some dirt and drips around the gas cap area on my body. My main issue has been struggling to start when hot. I posted this on a different thread last weekend, but it seems more related to this issue.

Here are the details:
Year: 1999 Toyota Land Cruiser
Location: Colorado (~6-7000ft)
Mileage: 203k

Here is what's happening:
I drive the car until the engine is hot, then shut it off. If started again immediately after turning it off, there are no issues starting. If I wait about 30 minutes, I have trouble starting. I turn the key, and it cranks for 5-10 seconds. Sometimes it will rev up to about 500 rpm, but then stall out. Sometimes I will continue cranking for 10+ seconds and the only way to start at this point is to hold my foot on the gas pedal. It will start, rev up, and then idle normal, drive normal, and be perfectly fine. I have had several cases where the car has stalled after idling for a long period of time (like in a drive thru), and then has trouble starting after it stalls. Once the engine is cool, it starts perfectly fine. Starting it first thing in the morning is never an issue. I have gotten several evap system codes (P0440 if I remember correctly) that go away for months at a time after being cleared.

I also checked the vacuum switching valve today, but was not able to blow air through the ports as the FSM specifies it should be able to do if functioning properly. I ordered this and plan to replace it next week.

I've started tracking ECT since reading this thread. So far, I was at 190-195F during a quick several mile trip at under 55mph with about 70F OAT. The other night, I was at 201-203F at 75mph and about 75F OAT. Currently doing an experiment with non-ethanol fuel this week. My radiator is looking dirty and it has numerous spots where fins are bent. Definitely planning to clean it, and need to decide if the bent fins are worth replacing the whole thing.

Here's other recent maintenance that I've done over the last year and a half or so (most in the last few weeks) trying to solve this problem:
- Replaced fuel pump (Denso)
- Replaced fuel filter
- Replaced fuel injectors (Denso) (as well as OEM o-rings, grommets, spacers)
- Replaced fuel pressure damper (OEM)
- Replaced fuel pressure regulator (OEM)
- Replaced engine coolant temp sensor (not OEM. Grabbed part from advanced auto parts on night)
- Replaced engine room junction box (OEM)
- Replaced PCV valve and hoses (OEM)
- Cleaned Throttle Body
- Cleaned MAF sensor
- Replaced gas cap
- Checked EFI relay resistance
- Checked camshaft position sensor resistance
- New spark plugs (Denso)
- Checked VSV functionality (could not blow air through ports and will replace soon)
- Timing belt, fan clutch, and coolant flush done around 180k

 

[2001LC]

Sound like dirty radiator, they get very dirty. I've cleaned on some for 3 hours and still get crud. If bent fins are what you see from the front. That is condenser and the smaller is transmission oil cooler. They'll likely be okay, unless more than about 50% closed.

VSV don't often go bad, but sounds like yours did. Make sure the vacuum line coming from VSV on intake to CC, is tight and not cracked. Also the line from back of air pipe (resonator) over intake to CC is good.

Stop by if your near South Denver, Greenwood Village area 80121. Just PM for contact info.

 

[CUBuffs]

On my 07 LX, @2001LC has done coolant service, thermostart, fan clutch, cleaned radiator; but have not yet seen difference in ECT, or fuel vapor issue. But trying to baseline and test to figure out where the issue is.
Now, with new fuel pump and filter from @2001LC, did some testing today on a trail around 8600 - 9000 FT and OAT 81
On the trail, ECT range was 187 - 207, could notice fuel smell and see vapor around the cap after around 30 minutes on the trail, and for the rest of the day. Could also hear boiling noise off and on, but did not have fuel stream out. Moderate trail, was in 4L the whole time. Started with a full tank of E10 gas.

I wanted to test if I could get the "no start" problem I had once a couple months ago (on a trail, shut off engine for a few minutes, restarted and ran very rough for a few minutes then stalled, couldn't restart for 30 mins; removed the gas cap and had fuel streaming out).

I did have another "no start" issue a week ago, before the fuel pump replacement, but that was a little different - I shut the engine off, then took gas cap off to check for boiling/venting, which it was, then it wouldn't restart for maybe 20 minutes.

So today, did the same trail as last week, similar OAT, got to same spot on trail and turned off engine. Waited 5 mins, and it restarted fine. Then I was thinking about last week, so I took the gas cap off, let it vent for a minute, it restarted with rough idle then stalled after a few seconds and wouldn't restart. I vented the cap until I couldn't hear any more noise, and after 20 minutes it started up fine.

I kept going on the trail and tested this 6 times over the next 3 hours. Truck would run great, I would stop, sometimes let it idle for a few minutes, shut off engine, let it sit for 1 - 10 minutes, and it would always restart fine. Would do a few shut off / restarts, no problem. Then I remove the gas cap, let it vent for 1 - 2 minutes, put cap back on, and 4 out of the 6 times, it wouldn't restart. Anywhere from 5 - 20 minutes later it would start up fine and run fine. I would usually leave the cap off until the venting slowed or stopped, but once I put the cap on with strong venting and boiling noise, truck started fine after 5 minutes (could still hear some boiling too).

Not sure what that all means, other then I won't be doing "preventative" gas cap venting... but seems like too little or too much pressure, or rapid changes can be issues.
And if anyone feels like trying that in their truck, let me know if it happens to you. My family thinks its odd I've twice headed out alone on a trail trying to break down, so keep that in mind.. be safe.. at least I saw multiple jeeps on the trail if I needed a "ride of shame"

 

[2001LC]

On my 07 LX, @2001LC has done coolant service, thermostart, fan clutch, cleaned radiator; but have not yet seen difference in ECT, or fuel vapor issue. But trying to baseline and test to figure out where the issue is.
Now, with new fuel pump and filter from @2001LC, did some testing today on a trail around 8600 - 9000 FT and OAT 81
On the trail, ECT range was 187 - 207, could notice fuel smell and see vapor around the cap after around 30 minutes on the trail, and for the rest of the day. Could also hear boiling noise off and on, but did not have fuel stream out. Moderate trail, was in 4L the whole time. Started with a full tank of E10 gas.

I wanted to test if I could get the "no start" problem I had once a couple months ago (on a trail, shut off engine for a few minutes, restarted and ran very rough for a few minutes then stalled, couldn't restart for 30 mins; removed the gas cap and had fuel streaming out).

I did have another "no start" issue a week ago, before the fuel pump replacement, but that was a little different - I shut the engine off, then took gas cap off to check for boiling/venting, which it was, then it wouldn't restart for maybe 20 minutes.

So today, did the same trail as last week, similar OAT, got to same spot on trail and turned off engine. Waited 5 mins, and it restarted fine. Then I was thinking about last week, so I took the gas cap off, let it vent for a minute, it restarted with rough idle then stalled after a few seconds and wouldn't restart. I vented the cap until I couldn't hear any more noise, and after 20 minutes it started up fine.

I kept going on the trail and tested this 6 times over the next 3 hours. Truck would run great, I would stop, sometimes let it idle for a few minutes, shut off engine, let it sit for 1 - 10 minutes, and it would always restart fine. Would do a few shut off / restarts, no problem. Then I remove the gas cap, let it vent for 1 - 2 minutes, put cap back on, and 4 out of the 6 times, it wouldn't restart. Anywhere from 5 - 20 minutes later it would start up fine and run fine. I would usually leave the cap off until the venting slowed or stopped, but once I put the cap on with strong venting and boiling noise, truck started fine after 5 minutes (could still hear some boiling too).

Not sure what that all means, other then I won't be doing "preventative" gas cap venting... but seems like too little or too much pressure, or rapid changes can be issues.
And if anyone feels like trying that in their truck, let me know if it happens to you. My family thinks its odd I've twice headed out alone on a trail trying to break down, so keep that in mind.. be safe.. at least I saw multiple jeeps on the trail if I needed a "ride of shame"

Dang, I'm surprised it still stalled. Did you put BG fuel system drier in fuel tank?

Go ahead and put the OEM radiator cap on now. See if any difference in ECT.

207 F, just seem to hot. We know for sure the belly pan is trapping heat, based on the wire housing heat damage. But even so, if we get ECT down that should not be a problem.

Is that wire to your fridge?

 

[CUBuffs]

Dang, I'm surprised it still stalled. Did you put BG fuel system drier in fuel tank?

Go ahead and put the OEM radiator cap on now. See if any difference in ECT.

207 F, just seem to hot. We know for sure the belly pan is trapping heat, based on the wire housing heat damage. But even so, if we get ECT down that should not be a problem.

Is that wire to your fridge?
View attachment 2403594

> Did you put BG fuel system drier in fuel tank?
Not yet, trying to track some down... no one in my area has it.

Will swap out radiator cap tomorrow!

Yes, that is the wire to rear fuse block and fridge. I have since moved it closer to the frame, it definitely gets hot right there - interestingly, that was the only area where the wire harness got heated and brittle and I ran it next to fuel lines most of the way.

 

[2001LC]

Yes, that is the wire to rear fuse block and fridge. I have since moved it closer to the frame, it definitely gets hot right there - interestingly, that was the only area where the wire harness got heated and brittle and I ran it next to fuel lines most of the way.

So you moved wire, before the last test run when you stalled again?
If not (moved after last test run) can you do another test run before rad cap R&R! Just so we keep to the step by step testing, eliminating one thing at a time.

 

[CUBuffs]

So you moved wire, before the last test run when you stalled again?
If not (moved after last test run) can you do another test run before rad cap R&R! Just so we keep to the step by step testing, eliminating one thing at a time.

I moved the wire a few weeks ago, before fan clutch and fuel pump.

 

[jerryb]

it's never a good idea to vent your tank with the cap. You wouldn't do it at the radiator, but people do it with a the other tank filled with flammable liquid with a higher than 1 ATA layer of gas on top lol.
At that point I think you can throw out any volume/temp and pressure calculations. Or the ppo2.
It's just bad all around.
Let it idle. It' might not cool faster but there won't be any shooting at the thermo nuclear weapons.