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Excessive pressure builds up in the tank after riding for an hour. Removed the dust seal kit and it doesn’t boil as violent.
changed the vent valve and that helped with the pressure issues. Removed the belly pan and used an inspection camera to see how much space was between the fuel tank and coolant lines - less than 3/4”. No heat shield!?
Anyone else experience this?
 

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This might help in this thread....
 

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I would love to take an IR photo to see the difference. Guys suggest gutting the cat and super coolants to first reduce generated heat, which makes sense, a tune is needed to limit backfiring. A lot of heat comes back from the radiator. There is a thin piece of rubber loosely covering the tunnel opening and master cylinder. I'm testing with an old tundra floor mat cutting around the coolant lines and tucking behind the shocks, brake line and covering brake master cylinder. All heated air going out the sides. I want to see what that return is, then address the coolant lines.
 

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I would love to take an IR photo to see the difference. Guys suggest gutting the cat and super coolants to first reduce generated heat, which makes sense, a tune is needed to limit backfiring. A lot of heat comes back from the radiator. There is a thin piece of rubber loosely covering the tunnel opening and master cylinder. I'm testing with an old tundra floor mat cutting around the coolant lines and tucking behind the shocks, brake line and covering brake master cylinder. All heated air going out the sides. I want to see what that return is, then address the coolant lines.
I'm going to do a ride with the hood off. Amazing the amount of heat that is trapped under it. Pull the hood sometime while the fan is running and you will see what I mean.
 

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I'm going to do a ride with the hood off. Amazing the amount of heat that is trapped under it. Pull the hood sometime while the fan is running and you will see what I mean.
If you are moving, I don't see how the heat is trapped. We have open wheel wells. If you open the hood, I think all the heat will come straight into the cab, if you don't have a windshield.

Doing a tune and taking my windshield off has made a big difference in cab heat. And I ride in +100* heat.
 

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The most heat is at the master brake cylinder (102 degrees) and behind the gas peddle. It defiantly needs insulated from blow back heat, I was going to suggest running with out the hood, but thought as Krawler, the heat would come up on the guys with no or limited windshield coverage.

Bob, I thought about suggesting a little hood scoop to increase air behind the radiator. If you are riding and don't detect increase in heat, leave it off. I should have took IR pictures with out the hood. Should tape off the conduit to keep mud out.



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Excessive pressure builds up in the tank after riding for an hour. Removed the dust seal kit and it doesn’t boil as violent.
changed the vent valve and that helped with the pressure issues. Removed the belly pan and used an inspection camera to see how much space was between the fuel tank and coolant lines - less than 3/4”. No heat shield!?
Anyone else experience this?
I’ve never even heard of boiling fuel, if it was my car it’d be at the dealer until the problem was resolved, or I got a full refund, that’s crazy not to mention dangerous, we’re in Yuma and I’ve ridden in 110 even 115 and not had that problem, yes it’s hot but not that hot.
 

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Class 1 Div IB flammable liquids (ethanol) has a flash point below 73 degrees and a boiling pt at or above 100 degrees. See temp posted above at passenger seat...yours is boiling too. By taking the pressure off the tank your making a happier place for your gasoline.
 

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I’ve never even heard of boiling fuel, if it was my car it’d be at the dealer until the problem was resolved, or I got a full refund, that’s crazy not to mention dangerous, we’re in Yuma and I’ve ridden in 110 even 115 and not had that problem, yes it’s hot but not that hot.
When ever u smell raw gas fumes there a problem.unlike automotive fuel systems that have a continuous fuel flow,meaning that once the desired fuel psi is accomplished the rest is recirculated back to the tank, I do not believe UTVs use this tried and true system.Therefore there is a great chance of vapor problems.The fuel is trapped in the supply until the injectors open.In automotive systems the fuel that is returned to the the tank is 10 times greater than the fuel the machine consumes.
 

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What really sucks is the fuel line runs through the hottest recorded area in the cab. Insulate (like the old Rhinos) or reroute your fuel line

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It’s amazing to me ,as how far these UTVS are behind the automotive technology.The fuel rails should have psi returns.the ecu s should have more input sensors.a knock sensor would be invaluable, run the timing up, lean it out, once u detect preignition,Back off.mass airflow pretty basic.and realize I haven’t worked on vehicle s since 2002
 

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Class 1 Div IB flammable liquids (ethanol) has a flash point below 73 degrees and a boiling pt at or above 100 degrees. See temp posted above at passenger seat...yours is boiling too. By taking the pressure off the tank your making a happier place for your gasoline.
Ethanol is the big problem.Depending on the percentage of ethanol,the boiling point varies greatly.Thats why anything with a carburetor is worthless in hot temperatures.its 114 degrees here today.It amazes me how the modern vehicles of today take it in stride,w the a/c still blowing cold!
 

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Ethanol is the big problem.Depending on the percentage of ethanol,the boiling point varies greatly.Thats why anything with a carburetor is worthless in hot temperatures.its 114 degrees here today.It amazes me how the modern vehicles of today take it in stride,w the a/c still blowing cold!
That being said I toke the KRX out last weekend.110 out no problem s, no modified vent valve completely stock ,early 2020 model.
 

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That being said I toke the KRX out last weekend.110 out no problem s, no modified vent valve completely stock ,early 2020 model.
Running mostly power lines and mining roads 20 to 50 mph.not graded by any means,perfect terrain for the KRX.a lot of it is part of the mint 400 off-road course.
 

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It’s amazing to me ,as how far these UTVS are behind the automotive technology.The fuel rails should have psi returns.the ecu s should have more input sensors.a knock sensor would be invaluable, run the timing up, lean it out, once u detect preignition,Back off.mass airflow pretty basic.and realize I haven’t worked on vehicle s since 2002
Kinda makes you think where they cut costs, my 93 cadillac has a more advanced efi system. However, Kawi isn't the only one guilty of this. Polaris's early efi on the Ranger etc used intake temp, engine temp, and barometric pressure to decide what fueling should be. In the end, it was basically a glorified carb with an auto choke. Our ranger wouldn't idle when it was sitting outside in the winter, had to keep on the gas for several seconds to keep it from dying. In the summer, idle would be rich. I don't think the KRX has any knock control or a wideband O2, maybe the Kraftwerks or dynojet guys would know more about it. If you want a good explainer on how efi works, Robot Cantina has several good videos on the subject with him installing an EFI kit on a Predator small engine.

BTW, the cadillac efi doesn't let you foul plugs from cold starts. You can start and stop the engine all day cold and it doesn't care. I think the hot fuel situation has an effect on hot starts and may lead to fouling plugs, but I haven't considered nor know enough on the subject to make that determination. I'm 99% sure the longer the engine cranks, the more fuel it adds (to a certain extent) until the engine starts. Heat soaking also can increase intake manifold temperatures which the computer tries to compensate for, then gets cool fresh air when cranking and can't react fast enough. But, I have no idea if the ECU even takes intake air temperatures into consideration in its fueling strategy. It's very easy with a limited efi system for something insignificant to cause "weird" issues. It would be nice if someone knowledgeable would do a writeup on how our ECU operates in this application and how advanced/limited it really is.

In reality, I just have to wonder why Kawi designed the engine to put the exhaust at passenger cabin instead of exiting out the back side of the motor, and have the intake on the opposite side. The whole thing really screams "we had a design for a motorcycle/atv engine and made it work, packaging and heat doesn't concern us, get this high margin product out the door". Of course, what other powersports/automotive product doesn't suffer from the same fate. The answer is: none of them.
 

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If you are moving, I don't see how the heat is trapped. We have open wheel wells. If you open the hood, I think all the heat will come straight into the cab, if you don't have a windshield.

Doing a tune and taking my windshield off has made a big difference in cab heat. And I ride in +100* heat.
You would be surprised. The more you can open things up, the more heat will escape before heating things up. Air flow through the radiator hits the firewall directly, and the hood keeps it there. When the fan is running, even more air is forced against it, open wheel wells or not. The flow is straight back from the radiator. Anyhow, I'm going to give it a try and see if it makes any difference.
 

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You would be surprised. The more you can open things up, the more heat will escape before heating things up. Air flow through the radiator hits the firewall directly, and the hood keeps it there. When the fan is running, even more air is forced against it, open wheel wells or not. The flow is straight back from the radiator. Anyhow, I'm going to give it a try and see if it makes any difference.
The only thing I'm concerned with out east here is tree limbs or similar getting in there. I will give it a try and see the difference with the IR CAM.
 
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