Gas tank building excessive pressure & fuel smell. Dangerous for sure! Why does this happen? (2 Viewers)

[95Fantasma80]

today i climbed up sequaio national park from about sea level to 6k feet in 100 degree weather didn't get to 80 degrees until i reached top.

My coolant topped out at 225 running AC, and trans temp reached 230 when i would turn off AC to bring the temps down...this was slowly gaining elevation for an about 30 mins at 15-25mph after sitting in stop and go for 30 mins.

Once reached 6k elevation and destination, i smelled gas in cabin and out.

after a 1 hour hike got back in 100 and cruising around park to destinations coolant stayed under 195 and trans temp under 170, no gas smell remainder of trip.

 

[NearJetties]

Thought I’d provide additional anecdotal evidence.

I have a 98 and have been chasing an intermittent P0446 code (Evap control system vent malfunction). It’s been coming back on more frequently given recently—I assume because of the 90-95 degree heat for days on end. Most people seem to get a set of 3 codes.

Over time I’ve replaced all the vacuum lines, the gas cap, and the purge valve on the manifold (25860-50100) but the light keep coming back. Not immediately but eventually.

I replaced VSV (90910-12268) on top of the charcoal canister on Thursday. Left for a road trip the next day and put it through conditions that had been triggering it. Prolonged high temps, idling in a parking lot for extended periods to keep the pets cool. So far so good #fingerscrossed

Also, I don’t live and haven’t traveled to high altitude with the truck (yet) but we have traversed a mountain road 5 times with near empty and near full tanks since Thursday. It’s 5 miles with a quick up and down in the Adirondacks. It will make your ears pop a few times. That had set off the CEL once before.

I’ve only had a bit of tank pressure and no fuel smell except for a little bit when first opening the cap. After changing the last item and running through 3 tanks there seemed to be almost zero pressure. It was significantly cooler out though.

2.5 weeks ago I’m pretty sure I experienced the fuel boiling issue. maybe it was vapor lock but that’s not common on these.

It was 95+ and had been driving for 4 hours. Near or at sea level. Made a pitstop and kept the car idling in the parking space to keep the pets cool. Maybe for 15-20 mins tops. When pulling out of the spot the truck died. Fired up after a few seconds. Idled across the lot to get fuel and it died again. Again fired up after a few seconds. Both times it restarted but hesitated. Both times the wheel was turned almost all the way— maybe a coincidence but also could have been the additional power steering pump load. Once at the pump it kept kicking off the pump and had to be filled slowly. Hasn’t done it before or since. The CEL was already on with P0446 which had come one earlier in our trip. Pulled into a spot, popped the hood, let the truck cool, and cleared the code. Fired right up. Hopefully it doesn’t do it again since the P0446 problem seems to be solved but the two may also be unrelated. I didn’t think at the time to look at the ECT as the needle never moved.

-‘98 LC, 237k miles
-recent timing belt/water pump and cooling system service with the red Toyota juice by OTRAMM
-the truck is stock
-always get premium but with ethanol

I was surprised an hour long trail that I did recently didn’t set off the CEL. Nothing too extreme but definitely lots of fuel slosh. This was before replacing the purge vent and VSV. Temperature was around 90.

 

[abuck99]

today i climbed up sequaio national park from about sea level to 6k feet in 100 degree weather didn't get to 80 degrees until i reached top.

My coolant topped out at 225 running AC, and trans temp reached 230 when i would turn off AC to bring the temps down...this was slowly gaining elevation for an about 30 mins at 15-25mph after sitting in stop and go for 30 mins.

Once reached 6k elevation and destination, i smelled gas in cabin and out.

after a 1 hour hike got back in 100 and cruising around park to destinations coolant stayed under 195 and trans temp under 170, no gas smell remainder of trip.

Fwiw- even under a heavy load, climbing in high range and D, your trans and coolant temps peaking in the 220’s/230’s is not normal for a 2UZFe in a 100 series. I would chase down why your truck is not maintaining temps under 200 degrees.

 

[95Fantasma80]

Fwiw- even under a heavy load, climbing in high range and D, your trans and coolant temps peaking in the 220’s/230’s is not normal for a 2UZFe in a 100 series. I would chase down why your truck is not maintaining temps under 200 degrees.

Thanks, will look into this I'm due for a timing belt and associated parts like fan bracket. thermostat etc. last one was in 2010 and I'm at 100k since last done, i hope its just routine maintenance needed.

 

[Catskills]

Yesterday was my first full day of ethanol free tank. Temps at 107, going 75 mph, towing. I drove well over two hours, which was plenty of time for the issue to appear.

I'm also getting better mpg.

My truck likes this gas. I'm not going back.

 

[Jono85]

Down Under is most of your gas non-ethanol or have they legislated that most all gas is E10 like the States?
That hot (over 100F) and close to 5,000ft with E10 would expect that.

Hey mate,
We have 91 oct, 95 oct, 98 oct and E10 unleaded fuels at most service station (including diesel of course).

 

[Whoareu2200]

New gas cap 17 yrs old lol

 

[guardcompany]

UPDATE: Today we ran Mineral Creek (slow rocky uphill that seemed a lot rougher that last year, lots of spotting) to Engineer Pass (12,800ft) then later to California Pass (12,960ft) all with normal ethanol gas. Zero issues. Engine temp never got above 190. I kept the engine on at all passes. Zero gas smell. Night and day difference from last year! Last year in colder weather I had boiling fuel on half dollar which is nothing. Tomorrow is Ophir and Imogene and I’ll keep everyone posted. At this point I’m not even going to try non ethanol fuel.

UPDATE 2: Back from the mountains... The next day we ran Ophir and Imogene. Zero issues on Ophir (ECT was 190 or under) and when we got to Imogene I kept it in 4H a little too long and in the climb up I got to 199 for a few moments. Engine was just working too hard in the thin air. Put it in 4L and in 2 or 3rd gear and let the gears do the work on that climb. I quickly went down before 190. Zero gas smell, zero boiling, nothing. Even with normal 91 Ethanol gas! I never used non-ethanol gas. I can't tell you how nice it is to finish that climb and be sitting at the pass (13,111ft) and have not even a smell of gas. The entire trip I had no issues! Last year in colder weather I was leaking gas out of my fuel door and had fuel smell all 3 days of trails. I brought all the EVAP system parts ( both VCVs, hoses and CC) and didn't touch them.

My average ECT on all the trails was 188. I don't have any data on the pavement because I towed it out and back.

Was it the fan clutch? Fuel pump? My heat shield? The fuel lines being wrapped? The O2 sensors? A mix of everything? Not sure...

If I had to do it over again... assuming your radiator is new or in great working order I would have replaced the fan clutch and fuel pump first and then hit the trails and see. Fan clutch is an affordable replacement and I would replace it with OEM if you are anywhere over 150k and it hasn't been done. I noticed the biggest difference after the fan clutch even in just around town ECT. I agree with @2001LC that I believe this issue can be fixed by getting the engine to run cool like it's suppose to. Has anyone had boiling at 190 or below?

I'm going to go ahead and call this issue fixed for me for now. I will replace the EVAP system parts when I have time. Next test will be getting on a hot rocky trail early desert season.

 

[Austin Hot Shoe]

UPDATE: Today we ran Mineral Creek (slow rocky uphill that seemed a lot rougher that last year, lots of spotting) to Engineer Pass (12,800ft) then later to California Pass (12,960ft) all with normal ethanol gas. Zero issues. Engine temp never got above 190. I kept the engine on at all passes. Zero gas smell. Night and day difference from last year! Last year in colder weather I had boiling fuel on half dollar which is nothing. Tomorrow is Ophir and Imogene and I’ll keep everyone posted. At this point I’m not even going to try non ethanol fuel.

Did exact same run, no issues w non ethanol gas......no pressure issues the 4 days up in Silverton, even had 3/4 tank on one of the days.

 

[guardcompany]

Did exact same run, no issues w non ethanol gas......no pressure issues the 4 days up in Silverton, even had 3/4 tank on one of the days.

Nice. I forgot to mention I did it with normal 91 ethanol gas.

 

[Whoareu2200]

Just ordered Asin fan clutch and changed gas cap. Mines has 200k

 

[Austin Hot Shoe]

Nice. I forgot to mention I did it with normal 91 ethanol gas.

View attachment 2392604

Yep, 91 from station at triangle in Silverton

 

[kgrove]

Another data point - 2002 LC with about 181K miles driven at maybe 1K elevation.

A few days ago, the OAT was 118F and I was getting huge amounts of fuel smell after driving around town and local freeways. No fuel spilled from the tank and the tank would only hiss vapor for a second or two when I opened it.

The last couple days, the OAT dropped to more like 110-112F, and almost no fuel smell under the same driving conditions. It was the same fuel (87 octane), just a few less gallons in the tank.

For my conditions and engine setup, I've sort of bracketed the conditions where it happens. If this really is a fuel temp / boiling issue like it sounds,
there's almost going to be a binary relationship... you either experience the problem or you don't. One day can be just a few degrees hotter, the last fuel you bought has a slightly lower boiling point, or you drive a little faster (or slower), and that might be just enough to push you over the threshold into bad fuel smells.

I did have a similar fuel smell problem a few weeks back, and in hindsight those days were abnormally hot too. My prior LC was an '07 and it had bad fuel smells occasionally, and now that I look back on it after reading this thread, it was always on brutally hot days.

 

[2001LC]

WOW that is a very high OAT. Where is that?

Data point I'm most interested at this point if ECT (Engine coolant temp)?

Along with that is OAT and particulars of you 100 series, including yr and miles. ie stock or built. If built what type of gear you have on it and most importantly, on that count is, do you have a belly pan.

The fuel used is also a very important data point. But there seems no doubt blended fuel exasperated the situation.

 

[AlpineAccess]

WOW that is a very high OAT. Where is that?

Data point I'm most interested at this point if ECT (Engine coolant temp)?

Along with that is OAT and particulars of you 100 series, including yr and miles. ie stock or built. If built what type of gear you have on it and most importantly, on that count is, do you have a belly pan.

The fuel used is also a very important data point. But there seems no doubt blended fuel exasperated the situation.

Post history does Phoenix

 

[gungriffin]

I am coming to wonder if you are right about the ECTs being a contributing factor. This feels like a situation where all the components in the system start to get tired and then the margin for error is shrunk. I just got back from the San Juans. J1000 had no boil over issues on Black Bear or Imogene with ECTs approaching 200. The other person in the group had severe boil over issues on the climb to the passes of both of those trails. His ECTs were ~200 as well. A major difference between the two trucks was weight too. Truck 2 was probably 500 lbs heavier. J1000 was using 87 octane with ethanol. The other guy was using a blend of 91 and 87 with ethanol. The climbs to the passes are quite strenuous for our trucks. I was seeing ECTs of about 192 at that point with trans temps approaching 190. I had no boil issues. Both trucks were running a bit below 1/2 tank. Correction, both tanks were nearly full. See J1000s better description below

 

[guardcompany]

I am coming to wonder if you are right about the ECTs being a contributing factor. This feels like a situation where all the components in the system start to get a tired and then the margin for error is shrunk. I just got back from the San Juans. J1000 had no boil over issues on Black Bear or Imogene with ECTs approaching 200. The other person in the group had severe boil over issues on the climb to the passes of both of those trails. His ECTs were ~200 as well. The major difference between the two trucks was weight too. Truck 2 was probably 500 lbs heavier. J1000 was using 87 octane with ethanol. The other guy was using a blend of 91 and 87 with ethanol. The climbs to the passes are quite strenuous for our trucks. I was seeing ECTs of about 192 at that point with trans temps approaching 190. I had no boil issues. Both trucks were running a bit below 1/2 tank.

The truck with the severe boil over issues was also 200 or below in ECT?

I don't think it's a built truck issue. I had it when I was almost 100% stock and fully built out.

 

[gungriffin]

The truck with the severe boil over issues was also 200 or below in ECT?

I don't think it's a built truck issue. I had it when I was almost 100% stock and fully built out.

Right at about 200

 

[J1000]

@gungriffin, @bassguyry, and I did Black Bear and Imogene over the weekend. All our ECTs were pretty much the same. 180-190s most of the time and then up to 200F on the final climb of Imogene. Ry and I topped up our fuel immediately before doing Imogene and he had it boil over and come spewing out once we crossed about 13k feet leaving puddles on the ground. Mine didn't boil at all. Gungriffin didn't fuel up at the start because he has the 40gal LRA tank and was already sitting fat and happy. I put my hand on his tank and then on my own and I would estimate his tank was maybe 5-10 degrees cooler to the touch than my own fuel tank. My fuel temperature gauge read 113F at the top. I didn't dare go near Ry's truck but judging by the geyser it had to have been HOT.

Also, @suprarx7nut, for the first time in my ownership of this vehicle and after having refurbished most of my EVAP system, I finally have pressure in my tank! Several times over the weekend I was able to release a hiss out of my cap which I had never been able to do before. Not only that but as soon as the pressure is released you can hear the fuel start to boil up!



I did notice a steady stream of vapors bypassing the cap coming through the plastic ring on my filler neck.

In conclusion, I'm stoked and it looks like my problem with boiling is basically fixed. Just one last leak to figure out at the filler neck. The LRA 40 gallon tank by itself likely mitigates this issues by virtue of being a huge aluminum heatsink exposed to the air and also holding more fuel to begin with increasing the thermal mass. Adding it to my wishlist.

 

[suprarx7nut]

@gungriffin, @bassguyry, and I did Black Bear and Imogene over the weekend. All our ECTs were pretty much the same. 180-190s most of the time and then up to 200F on the final climb of Imogene. Ry and I topped up our fuel immediately before doing Imogene and he had it boil over and come spewing out once we crossed about 13k feet leaving puddles on the ground. Mine didn't boil at all. Gungriffin didn't fuel up at the start because he has the 40gal LRA tank and was already sitting fat and happy. I put my hand on his tank and then on my own and I would estimate his tank was maybe 5-10 degrees cooler to the touch than my own fuel tank. My fuel temperature gauge read 113F at the top. I didn't dare go near Ry's truck but judging by the geyser it had to have been HOT.

Also, @suprarx7nut, for the first time in my ownership of this vehicle and after having refurbished most of my EVAP system, I finally have pressure in my tank! Several times over the weekend I was able to release a hiss out of my cap which I had never been able to do before. Not only that but as soon as the pressure is released you can hear the fuel start to boil up!



I did notice a steady stream of vapors bypassing the cap coming through the plastic ring on my filler neck.

In conclusion, I'm stoked and it looks like my problem with boiling is basically fixed. Just one last leak to figure out at the filler neck. The LRA 40 gallon tank by itself likely mitigates this issues by virtue of being a huge aluminum heatsink exposed to the air and also holding more fuel to begin with increasing the thermal mass. Adding it to my wishlist.

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