You better read it againLet me see if I understand you right.
You say that you have 4 cruisers to drive and only 1 exhibits fuel problems.
Then the next sentence you say it's happened to yours alsoso we went from 25% to 50% in once sentence.
Gas tank building excessive pressure & fuel smell. Dangerous for sure! Why does this happen? (3 Viewers)
- Thread starter 2001LC
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Ok the rest says you're a Texan driving slow on a road trip and you have no data. You realize the temperature at which fuel boils on a mountain is not hot enough to boil in Texas, right? The fuel is still the same temperature.You better read it again
Altitude is another factor, right? Here it's almost sea level and over 95F ambient temp so far this summer. Just one boiling on day-to-day heavy traffic. And 3 out of these 4 including the one which has the issue were in silverton last summer and drove through the engineer and black-bear passes. Used non-ethanol fuel there and had no boiling issues. That's why I'm guessing the one boiling developed a cooling system issue recently.
Tank pressure buildup and hissing noise are somewhat common at filling up in summer here. Not just LCs. I don't count that as boiling as I can remove the gas cap and fillup without issues.
Wish we can put temp gauges on return lines and in the tank
. Any suggestions? Rerouting return lines in the engine bay is over my capability but heat shields are on my TODO list.
And that is why I followed your advice about wrapping fuel lines and heat shield on the gas tank by the cats. Solved my vapor lock and fuel boil problem. Replacing vapor canister, fuel filter, gas cap, radiator, etc etc did not stop the issues which I had experienced in Las Vegas heat and Colorado elevation for a good ten plus years. (I have owned my 2006 since January 2007). Best MUD advice I ever followed and there is a lot of good stuff on here.
I read your posts and that's why I'm going to put heat shields for and wrap return lines. Really appreciate your effort and contribution here!
Good to know! Mine nor the one boiling fuel in Houston don't run into vapor lock or spitting fuel from gas cap. So our symptoms are minor compared to yours. So heat shields and wraps definitely going to help.
I finally installed the heat shield membrane to the bottom of the 100 at the gas tank. I bough it a year ago. It has been good so far for the smell, but it hasn't gotten extremely hot this year yet. I will see how this does then do the other items on the list as needed if the smell continues.
This finally happened to me, was doing Cathedral Valley Loop trail in Capitol Reef National Park, it was 104F outside air temp on the gage, when I smelled the gas I pulled over and unscrewed the cap. I had to let the tank off vent for 10m (very loud and a ton of fumes, not the safest situation), the vapor pressure must have been extremely high. I would also have the problem that after long stretches on the interstate, when I stopped to refuel, the pump would keep auto stopping because the pressure was too high for the nozzle I guess and it thought I was already full. I'd have to wait 5-10m with the cap open to get the pressure low enough.
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- Thread starter
- #750
Engine coolant temp?
No, sorry that wasn't clear, outside air temp.
I had a similar situation. Went over a mountain pass and when I stopped for gas I noticed the fuel had been boiling. After letting the LC sit and cool down I then attempted to fill up and had the same problem (auto stop). I had one other situation where it boiled on my way home from work. I didn't notice until I arrived home. Unfortunately this was a year or so pre lock down and since that time I replaced the gas filter, gas gap, radiator and fan clutch. Since then there hasn't been a problem. However, I didn't set my phone app to log the data when it occurred, so all anecdotal.
- Thread starter
- #753
It was clear 104f was parks OAT on dash gauge.
I was asking: What was your ECT (Engine coolant temp)?
I ask; because very often correcting a high ECT, eliminates fuel boiling.
I have had my 100 for 4 years and have had this issue at least 3x each summer. This year, I am going cross country towing a teardrop and it has happened twice in NM, and once in AZ on this trip already. All PM has been done, and only have tried a new gas cap added. It is about 90 degrees and 6000 ft driving on I 40. No boiling out but it clearly was venting and started running rough and died. I did something different this time though, I filled up the tank with my Jerry cans in the truck til full and it started running normal again immediately. I think the gas pushed all the excess vapor out of the tank and got it back to normal. So I will just keep bringing extra gas to me which I would anyway .
Keeping tank full can cause issues also. When it heats up it can spout gas when you remove gas cap. Also gas can be forced up vent line and saturate the charcoal canister, which is really not good.
Edit: For a properly working EVAP system on a 100 the high tank pressure/ fuel spouting is typically only seen for E10 fuel at high elevation and temperatures.
I have done many runs in the San Juan Mts comparing E10 with non-ethanol fuel. On mine and friend's Cruisers when using E10 we see high tank pressure and fuel spouting when we open gas caps. When we use non-ethanol fuel, same ambient, we don't see tank pressures even at over 11,000 feet with a hot Cruiser from the climb.
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The VSV on the intake will get stuck and only barely open. So it never sets a code. The truck thinks it's working fine, it clicks, but it never vents the tank. The whole vent system is just a controlled leak of tank vapor into the intake. If you are getting boil over, something is blocking the path of the vapor to the intake - that's it, it is pretty simple, really. Replace the VSV first before you replace the more expensive bits. Muffler and exhaust leaks will also heat up the fuel in the tank - check all the exhaust bits and connections.
Filling to top isn't a good idea as others mentioned. But pumping cooler gas into the tank reduces the temperature and stop boiling if you can safely open the cap.
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In hindsight what I originally chalked up to bad gas was not, and is obviously this. I've read through this whole thread since we're now residents of Telluride sharing time between there and Atlanta. The LC will be primarily residing in CO so I'm paying close attention to this thread and will contribute as much as I can.
06 LC "Lucy", bought 2 years ago with 145k. Slee step sliders and 33" tires. Otherwise stock. Purchased in Seattle in 2020 and drove to Atlanta.
When traversing Vail Pass we pulled off at the rest stop there and upon cranking up again had vapor lock. Took about 15min then fired right up and never gave another issue since then. I can't say if there was gas smell but certainly no fuel gush. OAT was 100+ before we climbed to the pass, so a little cooler at the stop.
in GA my ECT is 192-196 in OAT 90+ which seems to now be the accepted standard for the later models. I do plan to clean out the radiators this weekend and see if this lowers any as @2001LC has successfully done but won't be concerned if it stays in that range. It'll be interesting to see what happens when Lucy gets to CO and experiences these different scenarios.
One thing I have not seen mentioned on topic with temperature is relative humidity. Not sure how much of an impact that would have on the fuel but in theory the drier climate (CO) will allow for much quicker evaporation than humid heat (GA). And if we're talking about water vapor in the gas having an impact, that has to play a part, right?
I have my scanner now set up to read ECT, FT, IAT, MPG, RPM, AT1&2, Evap VSV
In hindsight what I originally chalked up to bad gas was not, and is obviously this. I've read through this whole thread since we're now residents of Telluride sharing time between there and Atlanta. The LC will be primarily residing in CO so I'm paying close attention to this thread and will contribute as much as I can.
06 LC "Lucy", bought 2 years ago with 145k. Slee step sliders and 33" tires. Otherwise stock. Purchased in Seattle in 2020 and drove to Atlanta.
When traversing Vail Pass we pulled off at the rest stop there and upon cranking up again had vapor lock. Took about 15min then fired right up and never gave another issue since then. I can't say if there was gas smell but certainly no fuel gush. OAT was 100+ before we climbed to the pass, so a little cooler at the stop.
in GA my ECT is 192-196 in OAT 90+ which seems to now be the accepted standard for the later models. I do plan to clean out the radiators this weekend and see if this lowers any as @2001LC has successfully done but won't be concerned if it stays in that range. It'll be interesting to see what happens when Lucy gets to CO and experiences these different scenarios.
One thing I have not seen mentioned on topic with temperature is relative humidity. Not sure how much of an impact that would have on the fuel but in theory the drier climate (CO) will allow for much quicker evaporation than humid heat (GA). And if we're talking about water vapor in the gas having an impact, that has to play a part, right?
I have my scanner now set up to read ECT, FT, IAT, MPG, RPM, AT1&2, Evap VSV
For a quick test to see if you have issues that need repairing, run a tank of non-ethanol fuel. If it's like my 100 you won't have issues with it, if you do then maybe something needs repairing. When I run the trails in the San Juan's we base out of Silverton where the small station on the main drag carries non-ethanol premium, at least it has during my past trips. That stuff is good even over the high passes on the trails.
Very easy to test this in GA as I live intown within a dozen E0 stations around me and can get to 5-6K trails where we go in the Appalachian area.
