Gas/Fuel vapors/fumes visible from gas door

[bloc]

@TeCKis300 when you did your fuel pump job do you remember whether the return to the tank dumped back into the fuel pump bucket or into the larger tank? I seem to remember it focusing on the bucket to prevent fuel starvation at low tank levels and steep vehicle angles.. but that was from reading and researching online. I haven’t had one of ours apart yet.

Maybe it’s a question of degrees but I definitely boiled fuel multiple times without any extra skids, at cool mountain temps. Now there’s a good chance the fuel here was a big part of that equation.

Also possible that some people boiling and others not on a given trail could be different fuel sources.

 

[linuxgod]

@linuxgod can you think of any correlation between dorkel and lack of boiled fuel on the recent trails?

Or anyone else for that matter?

A snorkel would effectively take IATs off the table as a contributing factor.

I have a snorkel since ~2017 and I boiled this time on TOTW. I've had a slight issue before but nothing like this. After that incident on this trip boiling seemed worse throughout UT/CO.

 

[linuxgod]

Found this article with this curve:
View attachment 3375672

Gasoline Boiling Point: Facts You Need to Know

In this article, you will learn the blends and compounds in gasoline, their effect on its boiling point, as well as pressure’s effect.

punchlistzero.com

I haven’t been following this thread too closely so sorry if this has already been posted.

From the curve, at 140F return temp, the gas would be about 20% vapor. At normal driving conditions this would probably not be an issue as the tank temp would be less and the evap system would be doing its thing.

Now add high altitude plus 100F+ ambient temp, and 3 mph wheeling up a mountain it’s easy to see how how well get some boiling.

So why do some have issues worse than others? IDK but mods are probably part of the equation. It makes sense to me that full BB style skids may trap enough heat that the tank doesn’t cool like OEM and the fuel return temp could even be higher.

Interesting.

Skids probably influence the frequency/severity but I have Asfir skids which are thicker but barely more coverage than the factory stuff. So it's not *just* a skids/no-skids issue.

 

[2001LC]

I should have never mention "snorkel" dropping IAT. It was more just giving some background on conversation Joey and I had. In which he noted things that help cool engine of the 80 series. In that conversation, what was very import to this thread, IMHO. If fan clutch.

 

[TheGrrrrr]

My fuel boiled 2k miles after a new radiator, the exact same way it does with 90k on that radiator.

It is painfully obvious a healthy cooling system is important for a reliable vehicle, but the discussion seems to be headed toward the only real solution for this being to remove heat from the fuel before it returns to the tank.

New radiator 2k miles ago and this trip through Utah and Colorado was the worst boiling I've had. I'm convinced the BudBuilt skids are trapping heat, particularly the fuel tank skid. I think the skids are also trapping a lot of the cat heat as well. I know some of the fuel lines (not sure if return or send) run right next to the cat. On my drive to Hanksville from Flagstaff on July 4th the fuel was boiling really bad and the 2nd row floor was also very warm. Ambient temp were in the 90's and certainly elevation was significant, but I also got severe boiling at highways speeds between Kayenta and Hankville on UT-95. So bad that upon arrival to Hanksville, I couldn't put any fuel in the tank. I drove to an RV park and borrowed their water hookup to attach a garden hose and spray down the exterior of the tank and between the the tank and the skid. I ended up getting 14 gallons in.

Attached is all the data I collected on that drive into Hanksville.

 

[linuxgod]

I should have never mention "snorkel" dropping IAT. It was more just giving some background on conversation Joey, and I had. In which he noted things that help cool to 80 series. In that conversation, what was very import to this thread, IMHO. If fan clutch.

In fairness my IAT on TOTW was reading 120F. But I don't think on the 200 there's much benefit to a snorkel to reduce IAT unless you're driving as at crawl speed (or in gridlock) the airflow is so slow it seems to reach the same temps (about 20-25F hotter than actual ambient temp) by the time it hits that sensor.

Interestingly both @indycole and I had boiling issues and both of us were seeing an outside temp of 77F on the dashboard the entire run, despite the fact it most definitely got hotter out as the morning progressed. Cole had mentioned on the way up whenever his ambient temp gets stuck at 77F he expects to have to clear an emissions systems code.

 

[linuxgod]

New radiator 2k miles ago and this trip through Utah and Colorado was the worst boiling I've had. I'm convinced the BudBuilt skids are trapping heat, particularly the fuel tank skid. I think the skids are also trapping a lot of the cat heat as well. I know some of the fuel lines (not sure if return or send) run right next to the cat. On my drive to Hanksville from Flagstaff on July 4th the fuel was boiling really bad and the 2nd row floor was also very warm. Ambient temp were in the 90's and certainly elevation was significant, but I also got severe boiling at highways speeds between Kayenta and Hankville on UT-95. So bad that upon arrival to Hanksville, I couldn't put any fuel in the tank. I drove to an RV park and borrowed their water hookup to attach a garden hose and spray down the exterior of the tank and between the the tank and the skid. I ended up getting 14 gallons in.

Attached is all the data I collected on that drive into Hanksville.

Not sure whether to "like" this or frown but yeah you definitely had a lot more boiling issues than I did on most of the trip. I'd definitely pull that fuel skid for a bit to see if it helps. Honestly if you're not going to wheel for a bit I'd be tempted to pull all of them for a week or two and see if the issue goes away.

 

[7000ft]

New radiator 2k miles ago and this trip through Utah and Colorado was the worst boiling I've had. I'm convinced the BudBuilt skids are trapping heat, particularly the fuel tank skid. I think the skids are also trapping a lot of the cat heat as well. I know some of the fuel lines (not sure if return or send) run right next to the cat. On my drive to Hanksville from Flagstaff on July 4th the fuel was boiling really bad and the 2nd row floor was also very warm. Ambient temp were in the 90's and certainly elevation was significant, but I also got severe boiling at highways speeds between Kayenta and Hankville on UT-95. So bad that upon arrival to Hanksville, I couldn't put any fuel in the tank. I drove to an RV park and borrowed their water hookup to attach a garden hose and spray down the exterior of the tank and between the the tank and the skid. I ended up getting 14 gallons in.

Attached is all the data I collected on that drive into Hanksville.

Wow! I live in Flagstaff and have never experienced any fuel boiling to date. My third LC200 (2020 HE) with LRA 12.5g tank, ARB skid package, ARB draws and several other accessories adding weight to it.
Spent two weeks recently in CO (loaded) up to 14,000 ft and didn't even get any fumes out of either tank.
Msybe just lucky.

 

[TheGrrrrr]

Attached is the data from the Moab side of Rimrocker headed toward Montrose. It was hot out and lots of low range, slow moving going up in elevation. All three trucks were boiling.

I think column X "Evap (Purge) VSV (%)" in the data probably needs to be correlated to some other data point(s) to identify the full range of variables at play, but anecdotally it seems to align with boiling gas pretty reliably.

 

[kcjaz]

@TeCKis300 when you did your fuel pump job do you remember whether the return to the tank dumped back into the fuel pump bucket or into the larger tank? I seem to remember it focusing on the bucket to prevent fuel starvation at low tank levels and steep vehicle angles.. but that was from reading and researching online. I haven’t had one of ours apart yet.

Maybe it’s a question of degrees but I definitely boiled fuel multiple times without any extra skids, at cool mountain temps. Now there’s a good chance the fuel here was a big part of that equation.

Also possible that some people boiling and others not on a given trail could be different fuel sources.

Yes, fuel blend maters a lot. Found this:

The solid lines are for gasoline with different Reid Vapor pressures which is a spec for different blends of gas. I think the solid green line is California gas which is required to have a Reid vapor pressure of 7. You can see that actual vapor pressure is pretty sensitive to the Reid # as well as temperature.

Also consider that the barometric pressure at 9000’ elevation is 10.4 psi. Return gas at 140F would be boiling pretty good at 9000’.

Gasoline - Citizendium

en.citizendium.org

Correlations for Conversion between True and Reid Vapor Pressures (TVP and RVP)

» Correlations for Conversion between True and Reid Vapor Pressures (TVP and RVP) |

www.jmcampbell.com

I think the physics is pretty clear and easy enough to understand. IMO, the key is to cool the return gas and not let the heat just build up in the first place.

 

[TeCKis300]

@TeCKis300 when you did your fuel pump job do you remember whether the return to the tank dumped back into the fuel pump bucket or into the larger tank? I seem to remember it focusing on the bucket to prevent fuel starvation at low tank levels and steep vehicle angles.. but that was from reading and researching online. I haven’t had one of ours apart yet.

Memory is a bit fuzzy but I think you're right that the return line did dump into the bucket. There seems to be a jet pump that further siphoned into the bucket. International setups with a aux tank have yet still another jet pump to siphon from the remote tank.

Here's a pic and all lines lead into the bucket. In our setup, 1 black line is superfluous as it's meant for an aux tank we don't have.

I should have never mention "snorkel" dropping IAT. It was more just giving some background on conversation Joey and I had. In which he noted things that help cool engine of the 80 series. In that conversation, what was very import to this thread, IMHO. If fan clutch.

I'm actually glad you mentioned it. While it's probably a lesser factor, it could still be a contributor to heat soak. One time idling for 30 minutes on a slope helping buddies ahead navigate an obstacle, I was seeing IATs almost double ambient. Usually it's only 10 degrees above. In mechanical systems, fuel and other fluids are often times used as heat sinks.

I've got a few heat wrap products coming in that I may use to insulate the fuel line. In some of the same key places that were identified in the 100-series.

 

[kcjaz]

Does anyone know the flow and pressure capacity of the OEM fuel pump on the tank? Also, what kind of pump is it? I would assume it’s a PD or diaphragm type pump? We need to know or at least have some idea of the flow and pressures of the system so we can size the air and fuel heat exchangers.

The little plate and frame HXs like the one @FerrisBueller posted above are very efficient and small compared to shell and tube HX. We just need to know how much heat we are trying g to reject.

I think an are cooler with its own fan potentially mounted in front of the radiator like the tranny cooler may work. I also wonder if one could use the AC circuit and use the fuel cooler as another evaporator in the circuit.

 

[TeCKis300]

Does anyone know the flow and pressure capacity of the OEM fuel pump on the tank? Also, what kind of pump is it? I would assume it’s a PD or diaphragm type pump? We need to know or at least have some idea of the flow and pressures of the system so we can size the air and fuel heat exchangers.

The little plate and frame HXs like the one @FerrisBueller posted above are very efficient and small compared to shell and tube HX. We just need to know how much heat we are trying g to reject.

I think an are cooler with its own fan potentially mounted in front of the radiator like the tranny cooler may work. I also wonder if one could use the AC circuit and use the fuel cooler as another evaporator in the circuit.

It's a pretty typical impeller type fuel pump running at ~42 psi. There's a multi-step fuel controller so the flow rate is somewhat variable.

Here's a teardown:

P0171: System too Lean (Fuel Trim)

forum.ih8mud.com

 

[bloc]

Memory is a bit fuzzy but I think you're right that the return line did dump into the bucket. There seems to be a jet pump that further siphoned into the bucket. International setups with a aux tank have yet still another jet pump to siphon from the remote tank.

Here's a pic and all lines lead into the bucket. In our setup, 1 black line is superfluous as it's meant for an aux tank we don't have.
View attachment 3376442


View attachment 3376424

Thinking through this between the return line dump and the siphon pump I’m betting the strategy is to have the bucket constantly full to the point of overflowing into the larger tank.

It’s not very relevant to boiling the main tank but it could be for measurement.. it seems the fuel being pushed into the rails may not be the coolest fuel in the tank. And this has me wondering whether we need another fuel temp input

 

[TheGrrrrr]

So, I'm back to this line of thinking:

• Remove fuel skid and drill polka dot pattern of 1" holes spaced 1/2" apart, effectively making it more like the factory skid only more holes.
• Similar (but far less) drilled venting for the skid that covers the catalytic converters
• Heat shield between the cat and fuel line, also a shield separating the fuel tank from the other skids where I think a lot of heat is building up.
• Replace canister and filter to ensure we start with fresh components.
• Final option is the fuel cooler with integrated fan wired to a bluetooth relay for the return line. Maybe something like IFTTT to connect an OBD reader to trigger the fan upon the PID "Evap (Purge) VSV (%)" returning any value above 0%. Mount where the spare tire used to be, maybe fashion a splash guard to limit water exposure.

This one looks like it would work, but ned to determine the right fitting size to ensure proper flow.: Amazon product ASIN B001QITRBS

 

[linuxgod]

So, I'm back to this line of thinking:

• Remove fuel skid and drill polka dot pattern of 1" holes spaced 1/2" apart, effectively making it more like the factory skid only more holes.
• Similar (but far less) drilled venting for the skid that covers the catalytic converters
• Heat shield between the cat and fuel line, also a shield separating the fuel tank from the other skids where I think a lot of heat is building up.
• Replace canister and filter to ensure we start with fresh components.
• Final option is the fuel cooler with integrated fan wired to a bluetooth relay for the return line. Maybe something like IFTTT to connect an OBD reader to trigger the fan upon the PID "Evap (Purge) VSV (%)" returning any value above 0%. Mount where the spare tire used to be, maybe fashion a splash guard to limit water exposure.

This one looks like it would work, but ned to determine the right fitting size to ensure proper flow.: Amazon product ASIN B001QITRBS

One at a time but yet that’s what I’d do. I don’t think I’d go the IFTTT rouge though, I’d just measure fuel temps and once I had an idea of what is/isn’t reasonable I’d look for an N.O. thermostat that could just trigger the fan on when the temp hits a certain point.

 

[bloc]

One major advantage of the fluid/fluid cooler is any mods to fuel line routing will be very minimal. The additional lines will be water/coolant so if they aren’t isolated from edges/vibration like factory parts all that happens is coolant leaks out.

Having to run new fuel lines all over the place is a primary reason I haven’t already installed an air/fluid cooler with fan.

Also with fluid/fluid or air/fluid.. why not just have power be applied any time the engine is running? We aren’t going to over-cool the fuel.

One more thought. We really should measure whether and how much heat is being added between the rail and tank before we base a solution on mods in that area. We haven’t confirmed that. I hope to soon, but only have medium additional skids to impact things.

 

[OnGrid200]

I'll add in with my experience. My Toyota service in fort Collins said that just changing the charcoal canister should fix it so I did this over the winter. Not that it matters but added snorkel a few weeks ago. I do have full BB aluminum skids and have for a long time. No boiling issues UNTIL today at about 90f ambient and 8000ft. Low range and slow speeds. My other trips have had cooler and rainy weather but I was still hopeful that the canister fixed the problem. So frustrating.

 

[TeCKis300]

I'll add in with my experience. My Toyota service in fort Collins said that just changing the charcoal canister should fix it so I did this over the winter. Not that it matters but added snorkel a few weeks ago. I do have full BB aluminum skids and have for a long time. No boiling issues UNTIL today at about 90f ambient and 8000ft. Low range and slow speeds. My other trips have had cooler and rainy weather but I was still hopeful that the canister fixed the problem. So frustrating.

In my learning of the system, the charcoal canister can't do much to help. It has limited ability to absorb fuel vapors, and the primary job is to handle vapors when parked. When the engine is running the engine generally ingests the fuel vapors and recharges the canister via the purge valve. In situations with heated fuel and lower atmospheric pressures, the fuel vapor is almost endless and the Reid Vapor pressure of the fuel is so high that the engine ECU closes both vent VSV and purge VSV in an attempt to pressurize the system to manage and contain vapor pressures, and keep fuel from ultimately boiling. Though I've also seen where it keeps the canister vent open too and is venting pressure.

It can get to a threshold that then exceeds the pressure capability of the fuel system at which point it will vent through the gas cap. That's the pressure relief safety valve.

The only control we have for a nominally working fuel system is to manage heat input into the fuel system.

 

[bloc]

The only control we have for a nominally working fuel system is to manage heat input into the fuel system.

This is the way.

Also I got curious and looked it up. Per EPA specs the cap needs to vent at only 1psi relative to the atmosphere around it. I'm not really sure what I expected given the massive surface area of the tank absolutely requiring pressures not get too high.. but.. wow that is low.

I still need to go through all the videos I took of fuel temps vs ambient, but what did occur to me during the trip is we need different data. I'm thinking fuel pump module outlet, fuel rail outlet, fuel pump module return inlet. Optionally find a way to get the fuel temp inside the tank itself.. perhaps someone can tell me whether a surface thermocouple on the tank skin would accurately reflect FUEL temp in the tank. I'd try to put this where it isn't getting radiant heat from the exhaust or anything, but to those that understand this stuff.. does a surface thermcouple on the outside of a black plastic tank accurately (enough) reflect the temperature of the fluid within it? This would really cut down on the difficulty (and safety risk) of hanging a wire into the tank.