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DT400

Fuel boiling in tank.

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You read that right the fuel is boiling in a plastic tank. You can hear it and you can see it.
Anyway after riding on some steep very slow trails (1st and 2nd gear) at about 80-85 deg and about 9500 ft the fuel will start to boil in the tank, I had this problem and so did my friend with a 2006(?) Rancher.
You can tell the fuel is boiling at the petcock.
All of the engine/exhaust shielding is in place on both machines.
I am assuming the exhaust heat is being transferred to the fuel by the metal of the petcock.
I am guessing that gas boils at about 173 deg (at 9500ft) depending on octane and methanol percentages it may be less.
Has anyone else experienced this?
What have you done, if anything to remedy this?
I am planning on some type of extra shielding but haven't decided on what exactly.

2003 Rubi.

Darrell

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is the tank venting ?. i've never been through gas boiling in any atv i've ever owned.

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please take the time to introduce yourself in the new member section before posting, thanks !.

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28 minutes ago, shadetree said:

is the tank venting ?. i've never been through gas boiling in any atv i've ever owned.

Yes it was definitely venting. Plus when you took the gas cap off you could look in and see the fuel boiling around the petcock. And like I mentioned it wasn't just mine that was doing it my friends was to. Definitely odd. I don't know if it's just the gas that we have here in Colorado.  Right now in the super hot summer I have got a completely stock '90 Mustang that I have had gas bubbling out around the gas cap this summer when I run the AC when it's real hot and that never happened when I lived in Phoenix and it was a 120 degrees and we've only been hovering around 100 here in Colorado Springs.

 

Darrell 

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4 minutes ago, DT400 said:

Yes it was definitely venting. Plus when you took the gas cap off you could look in and see the fuel boiling around the petcock. And like I mentioned it wasn't just mine that was doing it my friends was to. Definitely odd. I don't know if it's just the gas that we have here in Colorado.  Right now in the super hot summer I have got a completely stock '90 Mustang that I have had gas bubbling out around the gas cap this summer when I run the AC when it's real hot and that never happened when I lived in Phoenix and it was a 120 degrees and we've only been hovering around 100 here in Colorado Springs.

 

Darrell 

you got me then ?..never had it happen to me.

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Is the petcock scorching hot? It would have to be to be at 173.  That would burn you quick.  Your gas tank likely melts at less than 300 if I had to guess.   Depends on plastic it is made of.  

 

does your rancher have a fuel punp?
 

quick google got me this.  
 

Altitude also has a major effect on pump cavitation. ... The lower the pressure of a gas above a liquid — as happens at higher altitudes — the lower the temperature at which the liquid will boil. This effect increases the likelihood of water turning to a gasinside a pump, potentially leading to damage from cavitation.

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My Dad had a 56 Chevy and  then a 65 Impala , both of them I remember having wooden clothes pins clamped around the steel fuel tube at the carb , he use to talk about vapor lock , fuel boiling in the tube and vaporizing , the wooden clothes pin took the heat out of the tube and stopped it from happening -----try putting a wooden clamp around the petcock 

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6 minutes ago, 87Iroc said:

Is the petcock scorching hot? It would have to be to be at 173.  That would burn you quick.  Your gas tank likely melts at less than 300 if I had to guess.   Depends on plastic it is made of.  

 

does your rancher have a fuel punp?
 

quick google got me this.  
 

Altitude also has a major effect on pump cavitation. ... The lower the pressure of a gas above a liquid — as happens at higher altitudes — the lower the temperature at which the liquid will boil. This effect increases the likelihood of water turning to a gasinside a pump, potentially leading to damage from cavitation.

 

I don't know if the petcock was scorching hot you can't actually touch it on the Rubicon. The exhaust is almost directly below where the petcock is with only a small partial exhaust Shield and then a large plastic shield just underneath the tank. Not sure what you're referring to with the pump cavitation the 2003 is a gravity-fed carburetor. And my friends Rancher that is fuel injected did not have an operational problem ( neither of us did )just gas gurgling in the fuel tank just like mine. And yes I'm aware that altitude, heat, barometric pressure, octane and alcohol concentrations in the fuel will all affect the boiling point. Just wondering if anyone else has ever run across this issue.

 

Darrell

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6 minutes ago, Fishfiles said:

My Dad had a 56 Chevy and  then a 65 Impala , both of them I remember having wooden clothes pins clamped around the steel fuel tube at the carb , he use to talk about vapor lock , fuel boiling in the tube and vaporizing , the wooden clothes pin took the heat out of the tube and stopped it from happening -----try putting a wooden clamp around the petcock 

That's funny you mention the wooden clothespins. I do carry those in my toolbox in my truck for the guys who are still carbureted and have vapor lock problems it really does help. But I didn't have a vapor locking problem. Just a fuel boiling in the tank problem. Now that you bring it up I suppose there is a possibility that the rubber fuel line from the petcock to the carb was getting extra hot and Vapor was traveling back up the line into the tank but I do kind of doubt that theory since rubber does not transfer heat as well as metal.

 

Darrell 

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3 minutes ago, DT400 said:

That's funny you mention the wooden clothespins. I do carry those in my toolbox in my truck for the guys who are still carbureted and have vapor lock problems it really does help. But I didn't have a vapor locking problem. Just a fuel boiling in the tank problem. Now that you bring it up I suppose there is a possibility that the rubber fuel line from the petcock to the carb was getting extra hot and Vapor was traveling back up the line into the tank but I do kind of doubt that theory since rubber does not transfer heat as well as metal.

 

Darrell 

Even if you forget about the vapor lock side of the theory  , and just go with the removal of heat from the metal by transfer to the wood , it might make a difference if the petcock is were the heat is coming from ---- think about it like a hot water heater with the petcock acting like a heating element sticking into the tank 

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2 minutes ago, Fishfiles said:

Even if you forget about the vapor lock side of the theory  , and just go with the removal of heat from the metal by transfer to the wood , it might make a difference if the petcock is were the heat is coming from ---- think about it like a hot water heater with the petcock acting like a heating element sticking into the tank 

Yes you are correct. But there are better materials and better ways to go about blocking / reflecting the Heat. Since you can't actually see the petcock with the fuel tank installed you'd never know if your close Pin or whatever was still in place plus the plastic shield underneath is so closely fitted to the fuel tank I don't think there's any other room for something so big. Once I get it back together I'm going to create a better exhaust Shield that should do the trick. The real Puzzler is this is the first time I have ever had this problem with any gas powered vehicle I can remember.

 

Darrell 

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Being that it is happening down by the petcock could it be water?

 

Water (likely a water/ethanol) mix would sink and create a layer at the bottom of tank right?

 

Boiling point of gasoline is all over the place but the high-end is way over the BP of water.

 

According to Google gasoline BP is from 100-400F, water is 212F and ethanol is ~175F so if your tank was ~200F it was potentially boiling the "heads" of the fuel, water and ethanol or a mixture of the three.

 

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6 minutes ago, oh400ex said:

Being that it is happening down by the petcock could it be water?

 

Water (likely a water/ethanol) mix would sink and create a layer at the bottom of tank right?

 

Boiling point of gasoline is all over the place but the high-end is way over the BP of water.

 

According to Google gasoline BP is from 100-400F, water is 212F and ethanol is ~175F so if your tank was ~200F it was potentially boiling the "heads" of the fuel, water and ethanol or a mixture of the three.

 

Anything's possible and that's a possibility but I doubt it's water. If it was water and ethanol the water would mix with the ethanol and the ethanol would mix with the gas. Plus I run Heat in my tank every once in awhile to make sure there's no water in it. As well as the fact I have removed and drained the tank completely and there was no water to be found. I saw the same data as you for gasoline having a boiling point from 100 to 400 degrees. but found more data that said that Automotive gasoline is around 185 degrees Fahrenheit boiling point and I assume that's a standard temperature and pressure. So I extrapolated a little bit and figured that it may be around 175 degrees at the altitude I was at. Probably less actually. But again depending on the ethanol and octane mixes that could change the boiling point. I don't know what gasoline boils at 400 degrees but it certainly isn't anything you're putting in your car. Today's modern fuels are much more volatile than the stuff that was around in the 60s and 70s and even into the 80s which is why so many older carbureted vehicles have Vapor locking issues since the 80s. I remember dealing with this a lot in the 80s and 90s in carbureted Vehicles when the fuels were changing so much.

 

Darrell

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12 minutes ago, DT400 said:

If it was water and ethanol the water would mix with the ethanol and the ethanol would mix with the gas. Plus I run Heat in my tank every once in awhile to make sure there's no water in it.

 

Everything is a matter of concentration.

 

Did you know that you can remove the ethanol from gasoline by adding water?

Adding enough water to ethanol rich gasoline will force the EtOH into the water layer which will separate nearly fully with a bit of time.

The gas layer can be siphoned off and the purity will be increased lol 

 

Heet is also pure Methanol which will separate from the gas in a tank that is sitting.

A way to see this in action is to pour some gas into a clear bottle and add a small amount of water and heet.

Mix the contents of the bottle and almost immediately they begin to separate into a water/heet layer and gasoline layer. 

 

Not saying I'm laying all the cards on the table that it had something to do with water for sure just food for thought.

Could be as simple as a contaminated batch of gas from whatever supplier fills your local station.

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There is something else going on here... Last week me and Mr. Clean was in Siverton CO at 13k+... no trouble..I've got old equip. him newer??????

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1 minute ago, Derf40 said:

There is something else going on here... Last week me and Mr. Clean was in Siverton CO at 13k+... no trouble..I've got old equip. him newer??????

It's not just the elevation but a combination of things. After the boiling issue persisted for a couple hours in all of the slow, steep, rough stuff where the engines were making lots of heat and very little airflow and a hot day once we picked up the pace for a mile or less everything went back to normal and didn't rear its head once over the next 3 days.

 

Since it happened to two different machines one Rubicon 1 Rancher 1 carbureted one fuel injected. Fuel purchased from two different stations. Only persisted for about 3 hours on one very hot day I'm 99% sure that it was just that everything was very hot. The fans were constantly turning on and off but I never got a overheat light in my friends Rancher has a aftermarket digital dashboard with water temperature and he said it never got very hot. Whatever he meant by that I'm not sure.

 

My original intent for this post what's to see if anybody else had experienced this, which it seems no one so far has. And what they may have done to remedy it in the long run if it was a persistent problem. I am going to create another exhaust Shield just to give another layer of protection so it doesn't happen again. There doesn't seem to be any effect on performance it was just something I noticed and was wondering if it was common.

 

I do appreciate all of the different comments, ideas and their discussions.

 

Darrell

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i havent heard of methanol used in gas. there are some members here from Colorado. i'm at 600 Ft. Had to use clothespin's, myself in the old days.,

your near 9000ft. above me. i got an old machine, 2000.

any chance, the gas-tank is too close to the engine? some sort of heat shielding might help. Plenty out there, if ya want to look.

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4 minutes ago, LedFTed said:

i havent heard of methanol used in gas. there are some members here from Colorado. i'm at 600 Ft. Had to use clothespin's, myself in the old days.,

your near 9000ft. above me. i got an old machine, 2000.

any chance, the gas-tank is too close to the engine? some sort of heat shielding might help. Plenty out there, if ya want to look.

The tank is in the stock location...right above the engine and exhaust. I haven't heard of methanol being used in fuel the ethanol yes. I'm not sure to what degree I just haven't paid attention. I do know there's a couple of gas stations here in town that claimed to have pure gas but I think their specialty commercial type gas stations.

And yes I am going to do some kind of extra heat shielding to keep the exhaust from radiating upward towards the tank as much.

 

Darrell 

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heet  as @oh400ex mentioned is a gas treatment, and almost 100%? methanol..... used for mostly for winter time conditions, and to fight moisture in the fuel system, and fuel line freezing .... i doubt very much this is the issue sense DT400 never mentioned adding a fuel treatments..... personally... I've never seen / heard this happen....  till now.

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I've seen this several times in my life. This is most definitely a heat issue! I would insulate/wrap my petcock with something that blocks heat, As discussed already the high altitude  significantly reduces the boiling point of fuel which is very low at sea level. Alcohol blends lower the BP even more. Heat is the only problem. The first two times I saw fuel boiling was back in the late seventies or early eighties when we had 100% gas. It was very hot in Texas and my fuel was boiling in my 1952 Ford 8n tractor. Several other times it happened to my Mc Collough chain saw. I had it adjusted a little lean for higher RPM's and was running it very hard........one long cut after another. Turned it off and a few minutes later it wouldn't start. Thinking it was boiling fuel I pulled the rope many many times on full choke to force liquid fuel into the carb  and it started relunctantly but it started. This happened a few other times as well. Then about 15 years ago I bought a new Stihl 290 and worked the crap out of it the first day. I cut down one tree after another with out stopping. Occasionally it would die for no reason. A few pulls with and without choke it would start and run again. The stihl dealer said to use stihl oil because it runs cooler........they were correct.! The problem went away.

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My friend picked up a Yamaha Grizzly. Older unit but it had tin foil around the fuel line. Previous guy said the fuel would boil after it was run and then turned off. Just food for thought.

 

I did read somewhere else that someone also had a issue lately. Maybe a 3 wheeler forum(?) . It has been a hot summer overall.

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5 minutes ago, Big Bird said:

My friend picked up a Yamaha Grizzly. Older unit but it had tin foil around the fuel line. Previous guy said the fuel would boil after it was run and then turned off. Just food for thought.

 

I did read somewhere else that someone also had a issue lately. Maybe a 3 wheeler forum(?) . It has been a hot summer overall.

I would  " think " aluminum foil would intensify the heat  , unless you wrapped it with some kind of heat blanket under the foil ----- 

 

I like the Yamaha's myself , my second pick of atv would be a Yammy ,  Grizzly or Kodiak Special Edition ---  speaking of running hot  to start with , they run hot on slow rides ,   them Yammy's are made to stay moving and get some wind   without a relocation kit 

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Not gonna lie.. this is the craziest thing I’ve ever heard! U are seriously saying that if it gets too hot, gas will boil in a tank? In the 42 years of my life, this is new!! However I live in the cold north...

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Posted (edited)
24 minutes ago, Wheeler said:

Not gonna lie.. this is the craziest thing I’ve ever heard! U are seriously saying that if it gets too hot, gas will boil in a tank? In the 42 years of my life, this is new!! However I live in the cold north...

Yup. No joke. When you shut the ATV off you can hear it and when you remove the gas cap you can see it bubbling around the fuel petcock. Yes it is bizarre I've never experienced it before either. And in this one summer I've had it happen in two of my vehicles that are completely stock. I've been a mechanic on one thing or another from Machinery to aircraft and been working on vehicles since I was about 10 years old and  this is a first. I'm telling you the world's coming to an end.😜

 

Darrell 

Edited by DT400
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lol! your not too far from the truth.... when THEY started putting ethanol is gas.... they sure screwed us carberator guys over :-| 

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