Gas tank building excessive pressure & fuel smell. Dangerous for sure! Why does this happen? (3 Viewers)

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Hmm interesting stuff. What are your fuel temperatures?
Have never checked them. Just have the stock fuel system, no mods, and no shielding.
Is the fuel temperature available via OBD2, or does one need to install a sensor.
 
Another data point.
I was wheeling up Silver Canyon in Bishop, CA (just like another person on this thread). Conditions:
  • Elevation starting at ~4000 ASL to 11000 ASL in a very short distance. (90% of the ascent was in ~9mi, total uphill driving about 20mi to the Patriarch Bristlecone Pine grove).
  • Starting temperatures near 100 deg F at the base.
  • Starting fuel was about 1/2 tank, maybe a bit more.
When I got out of the truck, after the main ascent, the gas smell was strong. It made me check for leaks. I found none, and continued on. Above 11000 ft we stopped at our destination, and I still smelled the gas. I again checked for leaks. Then I carefully opened the filler cap. A lot of pressure came out, but no fuel, perhaps because I was at around 1/4 tank now. After venting the cap, there was no smell for the remainder of the trip.

Then I searched and found all these topics. crazy.
 
I replaced the purge valve on my '99 four years ago to try and combat this vapor issue. It is an expensive little part and it didn't change the amount of vapor release or pressure in the tank. In an weird turn of events, last week a P0441 triggered my CEL (first time I've ever had an emissions code). I replaced the purge valve with the original valve. Now I wait to see what happens.


I installed the LRA 40 gallon earlier this year and haven't made it to the high country yet to test. However, I do have a pretty substantial pressure release from the cap when I go to fill up when its hot outside (+90°). The rollover valve (77380-26010) and tube assembly (77018-60060) were replaced when I installed the tank. The LRA tank sits closer to the driver side cat than the factory tank, so I have some concern about heat soak. I might try some adhesive backed insulation material on the tank near the cat if there is a problem.

Which purge valve? Did you also replace evap lines? Purge valve cannot build enough pressure to actuate if lines are cracked. Mine were replaced with the valve.
 
Super dumb question ... is there any fuel additive that could be used as a band-aid? I would be happy to just dump an $8 bottle of something in my tank when I know I'm going to be headed to conditions likely to result in this condition.
 
Super dumb question ... is there any fuel additive that could be used as a band-aid? I would be happy to just dump an $8 bottle of something in my tank when I know I'm going to be headed to conditions likely to result in this condition.

Have you had issues with gas vapors?
 
Adds might make it worse. If at altitude, try running 85 or 87 octane as others posted success with that here.
 
Yup. Stong smell, pressure and vapors. Never had gas flowing from the fill neck though!
If you get down to South Denver drop by, I'll take a peak.

I'd encourage you the monitor engine temp meantime.

Anyone with this issue come on by.

Another data point.
I was wheeling up Silver Canyon in Bishop, CA (just like another person on this thread). Conditions:
  • Elevation starting at ~4000 ASL to 11000 ASL in a very short distance. (90% of the ascent was in ~9mi, total uphill driving about 20mi to the Patriarch Bristlecone Pine grove).
  • Starting temperatures near 100 deg F at the base.
  • Starting fuel was about 1/2 tank, maybe a bit more.
When I got out of the truck, after the main ascent, the gas smell was strong. It made me check for leaks. I found none, and continued on. Above 11000 ft we stopped at our destination, and I still smelled the gas. I again checked for leaks. Then I carefully opened the filler cap. A lot of pressure came out, but no fuel, perhaps because I was at around 1/4 tank now. After venting the cap, there was no smell for the remainder of the trip.

Then I searched and found all these topics. crazy.
Did you get engine temp during this trip?
 
Which purge valve? Did you also replace evap lines? Purge valve cannot build enough pressure to actuate if lines are cracked. Mine were replaced with the valve.
The purge valve (9091012268) you listed as the repair for your vehicle is on the vapor canister. That is what I replaced 4 years ago when my canister was making horrible groaning noises after long drives. I've also replaced the short lines on the vapor canister to the purge valve and from the canister to the intake manifold and to the air intake tube.
 
Have never checked them. Just have the stock fuel system, no mods, and no shielding.
Is the fuel temperature available via OBD2, or does one need to install a sensor.

I would like to know this as well.
 
Another data point.
I was wheeling up Silver Canyon in Bishop, CA (just like another person on this thread). Conditions:
  • Elevation starting at ~4000 ASL to 11000 ASL in a very short distance. (90% of the ascent was in ~9mi, total uphill driving about 20mi to the Patriarch Bristlecone Pine grove).
  • Starting temperatures near 100 deg F at the base.
  • Starting fuel was about 1/2 tank, maybe a bit more.
When I got out of the truck, after the main ascent, the gas smell was strong. It made me check for leaks. I found none, and continued on. Above 11000 ft we stopped at our destination, and I still smelled the gas. I again checked for leaks. Then I carefully opened the filler cap. A lot of pressure came out, but no fuel, perhaps because I was at around 1/4 tank now. After venting the cap, there was no smell for the remainder of the trip.

Then I searched and found all these topics. crazy.
I would expect that under those conditions and my LC would do the same running E10, actually think it has on a trip up Silver Canyon.
If I could get non-ethanol over there would expect no issue on that trip.
Maybe we need to try a fuel chiller, for those running a CO2 tank for tire inflation this looks interesting.
Fuel Chilling System
 
If I could get non-ethanol over there would expect no issue on that trip.

E0 gasoline/petrol:

Screenshot 2020-07-15 at 9.19.00 AM.png
 
If you get down to South Denver drop by, I'll take a peak.

I'd encourage you the monitor engine temp meantime.

Anyone with this issue come on by.


Did you get engine temp during this trip?

Thanks, @2001LC - I'll be making the trip from FTC to Silverton next week and I'll see about monitoring temps. I'll be towing a 4000# camper the whole way. I have the OBD Fusion app, pretty sure it can log that data. May try the low octane fuel as well.
 
We should be getting some pretty good data points in the next 2 weeks with everyone heading to the mountains, myself included. I'll be doing some last minute vacuum and switch replacement right before I leave. I'll make sure to monitor engine temp throughout the days.
 
For those wanting to post numbers here (Fuel Trims, Temps, etc) and don't yet have an OBDII Adapter (bluetooth) and App, which ones will "log" or "record" data?
I only plan to use it with my 2004 LX and my iOS (Apple) devices.
I do realize that TorquePro is still Android only.
Has anyone purchased a dedicated Android tablet just for the TorquePro app (what device do you use)?
But its abilities/features make me feel like a kid in a candy store:
 
That is so cool^^^^

If we can start collect these data point, especially engine water temp. It will get us just that much closer to understanding this issue.

If engine not running to spec, will chase our tail.

So concentrating first on:
Engine temp, then fuel trims is very helpful.
RPM and gear vehicle in at time, gives clues to driving condition.
OAT and altitude, seem too play really a big roll here.
CAT temp is 06-07 only IIRC.

Forget Fuel temps.
They'd would be great to have. But it is not available. We all need to add a device(s) to read it. If device added, I'd want to see both fuel going up and down stream to compare. Going into fuel rail. Coming out fuel rail (return line). But most of all, fuel as it enters fuel tank from return line. Since heat shield seem to give a great deal of benefit. It's clearly points to CAT is the major heat source. Which is hotter?? up or downstream would be interesting info.

Another thing I'm looking at in inspection now, is the gas cap door area. It's a clue if gunk, that vehicle is boil fuel building more pressure than system can handle.
 
For those wanting to post numbers here (Fuel Trims, Temps, etc) and don't yet have an OBDII Adapter (bluetooth) and App, which ones will "log" or "record" data?
I only plan to use it with my 2004 LX and my iOS (Apple) devices.
I do realize that TorquePro is still Android only.
Has anyone purchased a dedicated Android tablet just for the TorquePro app (what device do you use)?
But its abilities/features make me feel like a kid in a candy store:

I've downloaded Lifestyle Overlands data, tried the torque Pro app and Samsung tablet; problem for me is the getting PID specific programming info that work on our ISO based OBDII protocol; and then learning curve spending the time to program all that into the app; too much work for me. If blue driver has all that baked in and is plug & play even at $99 it seems "easier" option.
 
For those wanting to post numbers here (Fuel Trims, Temps, etc) and don't yet have an OBDII Adapter (bluetooth) and App, which ones will "log" or "record" data?
I only plan to use it with my 2004 LX and my iOS (Apple) devices.
I do realize that TorquePro is still Android only.
Has anyone purchased a dedicated Android tablet just for the TorquePro app (what device do you use)?
But its abilities/features make me feel like a kid in a candy store:

I've downloaded Lifestyle Overlands data, tried the torque Pro app and Samsung tablet; problem for me is the getting PID specific programming info that work on our ISO based OBDII protocol; and then learning curve spending the time to program all that into the app; too much work for me. If blue driver has all that baked in and is plug & play even at $99 it seems "easier" option.
I have bluedriver with my 03...it work great for what it picks up but is very dependent on year of vehicle and what data it can pick up. I wish the PID programming was easier too as I would go that route but instead got bluedriver. It give me some extra info (fuel trims, engine coolant temp) but hard to tell if it's been gamechanger data. Still happy I have it to see CEL/clear codes on trail if needed to get to civilization kind of thing, so it's more of an insurance tool for me that a data tool.
 

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