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

[jerryb]

one easy port would be the banjo bolt on either side of the crossover pipe for an electric sender.
I don't see an easy way to get one on the return to the tank line as it's that hard plastic hose.
I always got +1150°F and more on the stock cats on bare pipe forward of the heat shield and barely over 100°F on the fuel lines on the frame rail.
That's a gun though, not a probe. It's accurate enough for me, checked on the tranny pan compared to techstream.

LIke Buck said, I don't think seeing temp at the passenger rail would reveal anything too important.
On the fuel rails and crossover pipe I would think there's a cooling affect at speed with airflow and an affect at idle with the fan.
Not enough to sit and idle or creep around though. MAybe with fuel from 20 years ago, probably not today.
I don't think there is a magic pill to fit everyone.
Mine was a shield on the cat. Covering up the bottom from the cat to the frame rail with metal or plastic isn't the answer either.

all I can picture now is the ugly looking fuel tank skid plates posted on here. No, I don't think there will be a fix for everyone.

 

[2001LC]

Just adding another engine water temp data reading:

183 to 185 F touching on 187 F briefly. OAT 77f

This was a short 10 mile drive on city street, starting from cold engine (warm data omitted). Coolant system is at factory spec. as good as it gets for mileage, with a CSF radiator

Vehicle stats:
Emerald (see history in my signature) all stock Canada 2000LX 557,333 Km (353,228 miles) OAT 25C (77F) In last ~5,000Km: Coolant red/D-water, thermostat (82C), radiator cap (all OEM). Replacement radiator (CSF) OE. No vacuum leaks on engine (most lines replaced including intake gaskets and fuel injector bottom seals, new plugs Denso TT, New denso coils. Compression test normal for age, within limits. No back pressure test on CATS yet. Factor heat shield in place, CAT shield held sung with band clamps.
I've only 2 things remaining that I'm planning on doing to engine. Fuel injector off board testing and rebuilding and Fuel pressure regulator. I'm collecting long term data as I go.

 

[2001LC]

one easy port would be the banjo bolt on either side of the crossover pipe for an electric sender.
I don't see an easy way to get one on the return to the tank line as it's that hard plastic hose.
I always got +1150°F and more on the stock cats on bare pipe forward of the heat shield and barely over 100°F on the fuel lines on the frame rail.
That's a gun though, not a probe. It's accurate enough for me, checked on the tranny pan compared to techstream.

LIke Buck said, I don't think seeing temp at the passenger rail would reveal anything too important.
On the fuel rails and crossover pipe I would think there's a cooling affect at speed with airflow and an affect at idle with the fan.
Not enough to sit and idle or creep around though. MAybe with fuel from 20 years ago, probably not today.
I don't think there is a magic pill to fit everyone.
Mine was a shield on the cat. Covering up the bottom from the cat to the frame rail with metal or plastic isn't the answer either.

all I can picture now is the ugly looking fuel tank skid plates posted on here. No, I don't think there will be a fix for everyone.

I agree one size doesn't fit all.

But the first (OP), I worked on, seems solved. It was a 4 year long problem getting super bad on even short drives around town. Many mechaince worked, over the 4 years, all seem to have failed to address the basics.

Fuel routing around engine, should not be of concern. At least not in a stock engine and EVAP system.

We do have one common thread in all years stock, modified or build. I can't stress this enough. Engine needs to be well tuned and PM up to data. Granted most every vehicle I see is someone that's needing worked on, or one I've bought to restore. But even those that come to me for just front end work, say their engine in runs great and temp is normal have issue and temp is rarely normal. I almost always (99 out 100), find issue with engine & coolant systems.

Top engine issue I find in order:
Coolant system issues,
Vacuum leaks,
Spark
Air Intake.

Engine must be to spec. Than we can look at possible damaged cause by long term engine issue(s) or EVAP component failures.

One size doesn't fit all:

The biggest difference began in the 2003 model. With movement of CC to rear. Over filling gas or boiling fuel, in these may damage the CC. Toyota also made other change to the EVAP in 03 and seems again in 06.

I need to see more and tougher cases:
I hope to have some of these that damaged the EVAP or a component of EVAP failure. But to date, correcting the basic has stop fuel smell and excessive fuel heating in all I've worked on.

 

[jonand15]

Threads like this are why ih8mud is so fantastic.

I’ve had this happen three times to me now in the past year in my 2006 LX (once at about 10K on the trail, once driving 55MPH near Monarch pass, once after stopping in a parking lot after a 5 hour drive— all at 80 degrees plus temp). All situations required at least a 15 minute wait before I could restart the car. I bought the BlueDriver scanner and will start monitoring coolant temps and hope to contribute to the conversation. I’m also in the north end of CO Springs so I may be able swing by the @2001LC garage at some point if it’s an open invite

 

[2001LC]

Threads like this are why ih8mud is so fantastic.

I’ve had this happen three times to me now in the past year in my 2006 LX (once at about 10K on the trail, once driving 55MPH near Monarch pass, once after stopping in a parking lot after a 5 hour drive— all at 80 degrees plus temp). All situations required at least a 15 minute wait before I could restart the car. I bought the BlueDriver scanner and will start monitoring coolant temps and hope to contribute to the conversation. I’m also in the north end of CO Springs so I may be able swing by the @2001LC garage at some point if it’s an open invite

Sure come on by!
Invite is open to you, and all Mud.

 

[2001LC]

I just checked logs on a 2003 LX. This was recorded in Dec 19 after a coolant system flush and service. OAT would have been mild to cold.

183 to 187K

 

[gwatts]

We'll see if this helps any, my recent two data points after never having an issue before even at HIH with aux fuel tank.

1) Drove from Boulder to Floyd Hill to ride bikes (5,000' to 8,000') both tanks were full IIRC. Very warm in Boulder, not so much at 8,000 when I got there. Lots of climbing from Denver to Evergreen on I70, since re-gearing I can hold 70-75mph unloaded all the way with OD off. When I arrive I could smell gas. I could also hear the evap system working as well noise from the fuel door. I tried starting it again and it did. I opened the gas cap a little to let out vapor for a few minutes while I got kitted up to ride. Closed it and rode. 90minutes later started up fine and didn't hear or smell anything once home and down in elevation.

2) Two weeks ago driving from Boise, ID to Rock Springs, WY. Went from 2500' to 6300' over nearly 500 miles. This time the noise was louder, sure sounded like it was boiling. I had maybe 8-10 gallons left between the two tanks. Once I let out the vapor enough that I was sure it wasn't going to shoot off or spray fuel I tried to fuel up. I couldn't. The vapor was shutting off the fuel nozzle (I think that is why). I sat another 10-15 minutes before I could fuel up. I always stop fueling when the nozzle shuts off (previous fill). Truck stated right up and headed home. Almost forgot, the fuel transfer between tanks was wicked slow on this run. It barely kept up consumption. MPG was 12ish, so it should of filled me to Full as the aux tank ran out, like normal. I wonder if the boiling and vapor pressure caused it to suck some air and slow down transfer or something else. It was too loud to hear the clicks during normal operation or even the super load clicks of the pump when it runs dry.

One other point, the "not being able to fuel thing" happened once before, but there wasn't obscene pressure vapor coming from the tanks in that scenario, at least I don't remember there being any.

Also, of note. Driving 10+ hour days 10 days in a row from Seattle to the Arctic Ocean and to Anchorage in March this year, never had an issue with fuel vapor pressure when fueling, never heard any noise from the tanks or evap system. Chalk one up to OAT being part of the issue. Although the gas was high grade (low 80s) nor cut with ethanol that I remember. Fuel transfers were none issue too.

 

[Captramrod01]

Just an FYI for anyone curious. I have done every suggestion to solve this issue except for re-routing the return line and replacing a couple aging vacuum lines. We just got back from our yearly Telluride trip. On our way up I filled up with non-ethanol in Cortez and again in Silverton. Throughout the week I had zero vapor or boiling issues.

Thinking it may of been the heat shielding or replacing the charcoal canister I grabbed regular gas on the return trip. Sure enough when I got home the vapor was coming out of the gas cap.

As of right now the only thing I have left to do is replace vacuum lines. Not sure what to do if that does not fix the issue.

Additional Note: My cooling system is basically brand new. Fan clutch, radiator, hoses, pump, tstat all done in the last 10k with oem parts. I do not know my temps but I have to assume they were in spec?

 

[Jfoofighter16]

Just an FYI for anyone curious. I have done every suggestion to solve this issue except for re-routing the return line and replacing a couple aging vacuum lines. We just got back from our yearly Telluride trip. On our way up I filled up with non-ethanol in Cortez and again in Silverton. Throughout the week I had zero vapor or boiling issues.

Thinking it may of been the heat shielding or replacing the charcoal canister I grabbed regular gas on the return trip. Sure enough when I got home the vapor was coming out of the gas cap.

As of right now the only thing I have left to do is replace vacuum lines. Not sure what to do if that does not fix the issue.

You seem to have only thing that works for me no matter how many parts I repair/replace...E0 fuel! Unless I start boiling with E0 I am done chasing rabbits and throwing $ at this!

 

[phatdragon]

Following this, and tempted to start running non Ethanol fuel. Should we start a non ethanol gas station map especially around the high country. I live at 6000 ft. and generally run 88 octane (up to 10% ethanol) and go to 12000 ft in the summers often. {crosses fingers} I have yet to have this happen. 155k on the clock, base lined when I purchased it and have done regular maintenance since. I do get the lawn mower type smell from the charcoal canister on hot days, If that adds anything to the conversation.

 

[Jfoofighter16]

Following this, and tempted to start running non Ethanol fuel. Should we start a non ethanol gas station map especially around the high country. I live at 6000 ft. and generally run 88 octane (up to 10% ethanol) and go to 12000 ft in the summers often. {crosses fingers} I have yet to have this happen. 155k on the clock, base lined when I purchased it and have done regular maintenance since. I do get the lawn mower type smell from the charcoal canister on hot days, If that adds anything to the conversation.

Pure-gas.org and maverik gas station app usually cover finding E0 for me. Maverik seems to consistently carry E0 and their app also tells/confirms for individual locations. This of course assumes they are in your state. The pure gas site has a page for all 50 states so it's pretty comprehensive. Hope that helps!

 

[2001LC]

Interesting; Temps higher in rigs with bell pan and skids, than in stock rigs.

Silver beauty lite build (07LX 147K)
This rig came to me this week, for fuel boiling issue. First thing I did was run scan of engine coolant temp. I found temp running in 190s to 205F in short 1 mile drive. Open the hood, and I notice I could not touch the sides of radiator supports, near fenders. It was just to hot. I've never noticed that before. Subsequently I notice even the front fenders were hot to touch, but not the doors. So it wasn't the sun heating the metal, it was radiant heat.

I then flushed coolant and replaced thermostat. Engine seems well tuned with no vacuum leaks detected by visual inspection. It may have a cold engine minor intake gasket leak, common for a VVT. Radiator Cap is on BO (back ordered). Fan clutch seems okay. But not 100 % okay, and is 17 yr old with 145K. So may get some improvement by replacing it. So have that on BO also.

I found the engine temp varied as much or more with OAT, than a coolant service. The temps improved a little, but not much.
Pre coolant service 194 to 205F
After coolant service 189 to 196 . Radaitor support hot to touch

Merlot lite build (07LC 64K):
I also look back at Merlot (07LC 64K miles supper clean). I did nothing to coolant system except R&R Tees. I had data from earl June 2019 pre full Slee bell pan & skids and than again after install. I did not have OAT data or notes on the drives or where. But found it very interesting

Stock no skids on at the time; 185 to 187F
After bell pan & skids installed: 185F to 201F. Temp started out normal around 185F. Than keep climbing. After about 3 minutes of reach operating temp it never went below 189 F. In Fact it keep climbing for next 10 minutes to 201F. Most time temp was in the mid 190's and up.

Emerald (00LX w/350K) Coolant service done including new radiator.
I just ran some more logs on a Emerald, still getting the ~184 to 187 f.
I looked back at logs before doing coolant system service and I was running 189 to 196F.

 

[Captramrod01]

That is interesting. I have full Dissent skids. Could be contributing to the heat issue.

 

[d4nvu]

I also have full Dissent Skids and thought it had something to contribute. A few months ago I had my cats stolen underneath my truck and my LC shop had their exhaust guy weld on new cats so I wonder having non-oem cats would also add.

 

[Whoareu2200]

Would installing aux fan HELP. Like older K5 did.

To help vent out the heat from under the hood?

heat shield on fuel line in motor and heat shield next to cat for fuel lines.

 

[Captramrod01]

I have an aux fan on mine and it does not seem to help with this issue. It does help with getting the AC colder though.

 

[guardcompany]

Interesting; Temps higher in rigs with bell pan and skids, than in stock rigs.

Silver beauty lite build (07LX 147K)
This rig came to me this week, for fuel boiling issue. First thing I did was run scan of engine coolant temp. I found temp running in 190s to 205F in short 1 mile drive. Open the hood, and I notice I could not touch the sides of radiator supports, near fenders. It was just to hot. I've never noticed that before. Subsequently I notice even the front fenders were hot to touch, but not the doors. So it wasn't the sun heating the metal, it was radiant heat.

I then flushed coolant and replaced thermostat. Engine seems well tuned with no vacuum leaks detected by visual inspection. It may have a cold engine minor intake gasket leak, common for a VVT. Radiator Cap is on BO (back ordered). Fan clutch seems okay. But not 100 % okay, and is 17 yr old with 145K. So may get some improvement by replacing it. So have that on BO also.

I found the engine temp varied as much or more with OAT, than a coolant service. The temps improved a little, but not much.
Pre coolant service 194 to 205F
After coolant service 189 to 196 . Radaitor support hot to touch

Merlot lite build (07LC 64K):
I also look back at Merlot (07LC 64K miles supper clean). I did nothing to coolant system except R&R Tees. I had data from earl June 2019 pre full Slee bell pan & skids and than again after install. I did not have OAT data or notes on the drives or where. But found it very interesting

Stock no skids on at the time; 185 to 187F
After bell pan & skids installed: 185F to 201F. Temp started out normal around 185F. Than keep climbing. After about 3 minutes of reach operating temp it never went below 189 F. In Fact it keep climbing for next 10 minutes to 201F. Most time temp was in the mid 190's and up.

Emerald (00LX w/350K) Coolant service done including new radiator.
I just ran some more logs on a Emerald, still getting the ~184 to 187 f.
I looked back at logs before doing coolant system service and I was running 189 to 196F.

I've had this issue with and without full Dissent skids. In fact the single worst time I had fuel boiling out of my filler neck was without any after market skids. So I've ruled that out as a main cause, it could however be a factor in making a vehicle without a properly maintained cooling system run even hotter.

 

[guardcompany]

Within the last 2 months I've done:

O2 sensors (pre cat)
Fuel Pump (OEM)
Fan Clutch (OEM)
Built heat shield and wrapped fuel lines
Radiator is less than a year old (OEM)
Coolant is fresh and correct

Truck runs cool. Never see it get above 190.

I leave for Silverton on Sunday to run trails all next week. So I'll be testing with and without Ethanol free fuel. I will also be recording engine temp the whole time.

I was going to swap out EVAP system parts too before I leave but I want to do some testing and see what works. If I replace everything at once we won't get a lot data. Parts I have on hand with me to swap out during the trip are all the vacuum lines under the hood, VCS (2586050100) under hood, fuel pressure regulator (2328050050) and CC. All OEM parts. I'll keep everyone posted!

 

[Whoareu2200]

Within the last 2 months I've done:

O2 sensors (pre cat)
Fuel Pump (OEM)
Fan Clutch (OEM)
Built heat shield and wrapped fuel lines
Radiator is less than a year old (OEM)
Coolant is fresh and correct

Truck runs cool. Never see it get above 190.

I leave for Silverton on Sunday to run trails all next week. So I'll be testing with and without Ethanol free fuel. I will also be recording engine temp the whole time.

I was going to swap out EVAP system parts too before I leave but I want to do some testing and see what works. If I replace everything at once we won't get a lot data. Parts I have on hand with me to swap out during the trip are all the vacuum lines under the hood, VCS (2586050100) under hood, fuel pressure regulator (2328050050) and CC. All OEM parts. I'll keep everyone posted!

PRAYING TO THE LEXUS GODS TO FIX THIS ISSUE LMAO. Hopefully this works. I bet you have a few of us here soon as you come back waiting for results lol

 

[2001LC]

I've had this issue with and without full Dissent skids. In fact the single worst time I had fuel boiling out of my filler neck was without any after market skids. So I've ruled that out as a main cause, it could however be a factor in making a vehicle without a properly maintained cooling system run even hotter.

Yeah. I don't think one size fits all.

So again i say, first step for me is getting basic in-line. Then look for other cause and effect, if still issue(s) of boil fuel and/or high engine temp.

This 07LX that's running hot, is very clean and good running. Whereas in stock rig, I've corrected fuel boiling, by aligning basics. This 07LX coolant system, although due for service, wasn't that bad and did yield much when serviced. We'll likely R&R the fan clutch and get a reading on temp. We'll also likely R&R the fuel pump. As it did have a no crank start once recently. The will see. I suppose we could pull (PITA) the bell pan, as a test.

I'm wondering if the heavy metal bell pans & skids. Aren't reducing air flow and retain heat. We notice some aftermarket wiring run along fuel line by CAT and bell pan. The wire housing looks like it's melting. So some concern wire may be effective fuel lines by causing some additional heat or eve generating some extra heat.

Within the last 2 months I've done:

O2 sensors (pre cat)
Fuel Pump (OEM)
Fan Clutch (OEM)
Built heat shield and wrapped fuel lines
Radiator is less than a year old (OEM)
Coolant is fresh and correct

Truck runs cool. Never see it get above 190.

I leave for Silverton on Sunday to run trails all next week. So I'll be testing with and without Ethanol free fuel. I will also be recording engine temp the whole time.

I was going to swap out EVAP system parts too before I leave but I want to do some testing and see what works. If I replace everything at once we won't get a lot data. Parts I have on hand with me to swap out during the trip are all the vacuum lines under the hood, VCS (2586050100) under hood, fuel pressure regulator (2328050050) and CC. All OEM parts. I'll keep everyone posted!

This is interesting, you're running under 190 F, which is what I consider normal and good.
Is your "Dissent Skids" also a bell-pan like the Slee bell pan cover from rear of CAt to fuel tank?

Full Slee skids & bell pan.