Wheeling right now and my gas was spilling out of my gas cap. When I opened it the gas shot out on me. Then it just boiled for awhile.
Gas/Fuel vapors/fumes visible from gas door
- Thread starter kalieaire
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Yeah i was in shock it happened before but I would just open the gas cap and it would be fine but yesterday it shot at me. I had gas everywhere my shoes pants and hat. Here’s a pic of it I have a video but can’t post it. Oh and no LRA tank just a stock gas tank.
What elevation?
How full was the tank?
How long (in time) since you had filled up?
Regular or premium? Any idea of ethanol content?
I assume slow wheeling?
IMO the best way to handle video if you really want is to post it to YouTube. You can set it to private/unlisted and just post the link here.
Elevation was about 7-8000 ft I was in big bear California, just filled the tank before the run, I use regular California gas 87 octane I think it’s up to 10% ethanol, yes I was rock crawling I’ll try to post one up, it was bad kept boiling over for at least 15 - 30 min , it stopped when i got to lower elevation and a more cooler area. But it scared the crap out of me it was pouring out of the tank.
Sketchy. Really sketchy. Makes me wonder how the charcoal canister survives at all.
Mine has never been that bad, visibly anyway. But I’ve never been in that situation with the tank so full either. It sounded the exact same except that the boiling seemed to be happening further down inside the filler neck.
Edit: this has prompted me to order the thermocouples and reader I linked earlier. Leaving for Colorado this week so I’ll try to get some numbers on fuel supply and return temps. Won’t have a cooler yet, or any time soon realistically, but will be collecting some data.
Yeah it spooked me out , like I said I’ve had the smell of gas many times, I’d just take the cap off and you’d hear the air but never like this I was literally leaving gas on the trail and when I opened it it blew up enough to get on my hat, shorts, leg, sock, and shoes. I was getting high off the fumes wheeling. So I jumped on mud and read that it has happened to other people probably not as bad as me. I think it has to do with the gas I use , the temperature (it’s been hot in Cali) and altitude. But definitely not safe since I’m a smoker.
Pfsst. What's one more "unsafe" thing about smoking in the grand scheme of things? You might be overblowing this one.
Leaving for silverton today, will get some data on the road and trail
I've experienced this is big bear too.
It's important not to open the gas cap. The pressure the system builds helps manage vapor pressure. By opening the gas cap, pressure suddenly drops to atmospheric, which will cause the fuel to boil more vigorously.
Other things that can be done
- use 91 octane for it's reduced vapor pressure
- use low range
- avoid excessive idling
Some underarmor exascerbates this issue, but it can certainly happen even stock as I've experienced.
Looks like @bloc is on this, but we need to figure out strategic heat sheilding additions. The 100-series guys have figured this out reducing fuel temps by at least 25 degrees. Fuel cooler may or may not be the answer as most places under chassis just may be warm enough to put more heat into the fuel.
It's important not to open the gas cap. The pressure the system builds helps manage vapor pressure. By opening the gas cap, pressure suddenly drops to atmospheric, which will cause the fuel to boil more vigorously.
Other things that can be done
- use 91 octane for it's reduced vapor pressure
- use low range
- avoid excessive idling
Some underarmor exascerbates this issue, but it can certainly happen even stock as I've experienced.
Looks like @bloc is on this, but we need to figure out strategic heat sheilding additions. The 100-series guys have figured this out reducing fuel temps by at least 25 degrees. Fuel cooler may or may not be the answer as most places under chassis just may be warm enough to put more heat into the fuel.
If you can, you should consider wrapping a little insulation around those now that they're mounted. That will keep the ambient air temperature from affecting the probes, so the readings you get will be pretty much exactly the fuel temp at in the lines.
Really looking forward to seeing what data you get. I had been considering doing something similar.
I do have full skids also so that’s probably a factor
Something interesting I realized while under there is the fuel lines take a very winding route to get from the tank to the engine bay. They actually tuck into a small metal crossmember above the transfer case to get from the fuel tank frame rail to the other side.. I’d bet this area is a large portion of the thermal energy being added to the fuel, with it sitting directly above two exhaust pipes and the transfer case exposed to significant radiant heat then having all that surface area to conduct it into the lines.
My thinking is that there is so much liquid moving through those lines that they and anything (of little mass anyway) in direct contact with them will accurately reflect the temp of the liquid within. Plus it isn’t shown but there is a metal guard that gets mounted over that whole area which should reduce radiant heat transfer. I believe the guard is for markets with a fuel filter in that location.
I actually have a plan to test my theory for conductive heat transfer overcoming convective by shutting off the engine, letting everything heat soak and stabilize, then watch what happens when I start it again. I predict very quick temperature drop (to whatever the supply temp was before shutting down) on the supply line, and quick rise on the return line (as fuel gets heated by being in the rails mounted to the engine then returned to the tank).
Another option for all of this is to put them under the fuel tank access hatch. What I did was much easier though, and I didn’t particularly want to lift the middle carpet and disturb the seal for the hatch.
My thinking is that there is so much liquid moving through those lines that they and anything (of little mass anyway) in direct contact with them will accurately reflect the temp of the liquid within. Plus it isn’t shown but there is a metal guard that gets mounted over that whole area which should reduce radiant heat transfer. I believe the guard is for markets with a fuel filter in that location.
I actually have a plan to test my theory for conductive heat transfer overcoming convective by shutting off the engine, letting everything heat soak and stabilize, then watch what happens when I start it again. I predict very quick temperature drop (to whatever the supply temp was before shutting down) on the supply line, and quick rise on the return line (as fuel gets heated by being in the rails mounted to the engine then returned to the tank).
Another option for all of this is to put them under the fuel tank access hatch. What I did was much easier though, and I didn’t particularly want to lift the middle carpet and disturb the seal for the hatch.
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VERY preliminary data: when it’s 20 degrees cooler outside, the fuel is 30 degrees cooler, both supply and return. Up to 134F return sitting in ~10mph traffic at 93F ambient. 129F cruising at 75mph.
Anyone happen to know what the Vapor pressure of gasoline might be at those temps? I’m guessing on trail they’ll be significantly higher..
Other thoughts.. we should be able to see if heat is being added under the vehicle by measuring temp of the fuel supply line at the pump module exit, then at different points under the vehicle. If substantial heat is being added there that insulation/isolation would fix, we’d see temperature rise in that distance. If most of the heat is being added in the rails, this temperature would stay static, and a cooler on the return line to remove heat before returning to the tank would be appropriate.
Also, it occurred to me that techstream allows us to monitor “vapor pressure pump” and “vapor pressure (calculated)”. Anyone know if this includes the tank? The quick check I did showed ~705mmHg(absolute). If so I would be interested in any correlation with fuel temp and/or boiling activity. Maybe a use for a custom OBDFusion dashboard? Calling @linuxgod or @TeCKis300
Anyone happen to know what the Vapor pressure of gasoline might be at those temps? I’m guessing on trail they’ll be significantly higher..
Other thoughts.. we should be able to see if heat is being added under the vehicle by measuring temp of the fuel supply line at the pump module exit, then at different points under the vehicle. If substantial heat is being added there that insulation/isolation would fix, we’d see temperature rise in that distance. If most of the heat is being added in the rails, this temperature would stay static, and a cooler on the return line to remove heat before returning to the tank would be appropriate.
Also, it occurred to me that techstream allows us to monitor “vapor pressure pump” and “vapor pressure (calculated)”. Anyone know if this includes the tank? The quick check I did showed ~705mmHg(absolute). If so I would be interested in any correlation with fuel temp and/or boiling activity. Maybe a use for a custom OBDFusion dashboard? Calling @linuxgod or @TeCKis300
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I’ll see if I can figure out what sensor is used to determine pressure and/or if the FSM mentions another about expected or boundary fuel pressure values somewhere in the the troubleshooting sections. The dashboard itself would be trivial to create once we know what the parameters are
I just added them to my dashboard. And will take a look at my next drive. Though I'm in near freezing temps in Wyoming at the moment.
I'm not sure monitoring these will be all that useful. Perhaps to compare diff fuels in more controlled conditions? As it is, vapor pressure is a quality of fuel, and is pretty linear with temp.
I keep finding my way back to this thread, which probably means it's the right place for this post. (TL;DR: re-check LRA plumbing and install some kind of heat shield betwixt LRA and exhaust.)
After much help and encouragement from @TeCKis300 I've installed a new fuel pump assembly, repaired a botched LRA (24G) install, replumbed the vent-to-atmo portion of the evap/CC system, and bench tested the CC itself. All codes are cleared.
Final bit: it appears I'm having the 'too hot in the hot tub' issue with my resonatorless exhaust, which ends ~6" behind rear tire, down-vent. Syptoms, not necessarily related, include:
After much help and encouragement from @TeCKis300 I've installed a new fuel pump assembly, repaired a botched LRA (24G) install, replumbed the vent-to-atmo portion of the evap/CC system, and bench tested the CC itself. All codes are cleared.
Final bit: it appears I'm having the 'too hot in the hot tub' issue with my resonatorless exhaust, which ends ~6" behind rear tire, down-vent. Syptoms, not necessarily related, include:
- loud gong-like clunk sound from LRA soon after driving begins. Given that I have a degree in obviousness, I assume it's expansion as heat builds (but don't always hear it with road noise), and contraction as vapor condenses. Big sheet metal bowing out/in. The latter usually happens when meeting up at the trail head, and scares the snot out of everyone in earshot.
- The MPG display (estimator) resets with fueling, as expected. After adding fuel, if I don't have to stop and idle, I can get into the normal high-teens range. Once in high-teens and I get into city or stop-and-go traffic, I can watch the MPG readout drop at each reporting interval. Eventually, if I just sit there and idle, it goes to mid single digits.
- Since I just did all the work on the fuel system, I have not done a fill-up to first click (maybe don't, due to CC fouling?) and done an observed MPG test. That being said, it appears to actually use more fuel at idle, and performs normally at higher speeds.
- The fuel trims have very clearly been heading back to stoich; they were way out (lean banks 1 and 2) so the truck had been drinking a ton. Fuel pump replaced. Codes gone. Could be taking a long time to re-learn healthy fuel map settings. (will check via TS again tomorrow)
- Driving behavior is totally normal; no stalls or coughs or hickups.
- On cold start, in park, the idle does not settle into the 500 neighborhood for a long time. Usually, I have to drive a few hundred yards for this to settle down. (could just be evap/vent/valve system 'booting' up)
- CC is fouled enough to restric vapor traffic sufficiently to not vent the more-than-OEM volume of fuel vapor from factory and LRA tanks combined. I did the field manual tests; current activates the vent valve; did not do high-precision flow test procedures, but air came out where it was supposed to. (fix: heat mitigation where LRA and exhaust get cozy; if not remediated, go back to CC question)
- CC is ok, but same as above. (fix: same as above)
- Vent to atmo from CC is kinked somewhere, which *could* have happened when I reinstalled (just thought of this while writing, so this post may just be dumb)
- Unlikely: MPG estimator is lying due to an issue with some sensor from which it takes its input. (reminder, no codes or CELs)
- More likely: truck runs just fine with normal MPG at speed, but slow/idle conditions allow heat accumulation back by the LRA, overwhelming the CC (and CC might be fouled).
- Some issue with that secondary air system that sits under the front passenger side (two globes, I think; people talk about bypass mod)
- I mis-plumbed the LRA in some way. (I installed very carefully and tripple checked everything...but ish happens)
For the sheet metal issue, you could try to heat-shield the exhaust, or maybe just turn it towards the rear tire to push heat to the side. That said if the tank is flexing in an area you can access I suggest just getting a bit of U channel from Home Depot and trying to attach it to the tank. Welding is best but in this case you may just start with some gorilla glue and JB weld as all you really want is a bit of reinforcement to keep it from flexing. I do this when I’ve encountered HVAC duct that is flexing due to too much air pressure.
Ignore your MPG readout for now and do the manual calc method. FWIW this time of year in Chicago i get about 7-8 mpg in city driving, and maybe 12-13 on the highway. If you really want to watch your fuel consumption get an OBD2 port dongle and OBD Fusion on your phone and you can watch the instantaneous consumption
As far as cold start, do you mean it’s idling low or high? Mine idles high for several minutes. That’s normal. I think it sits around 650 RPMs or so once it settles down. Alternator kicking it up because I have seat heaters and stuff on is typical at idle too this time of year