Bad Gas

[W0QNX]

I doubt it's a vent line mainly because we have here 2 examples of a well vented tank (opened) bubbling away. It's boiling, plain and simple. It does that.

Mine has done this since new as did all 4 of my Honda Valkyrie's when they are hot. I think it's just the lower boiling point of good old blended fuel. ST1300 even will "heat" the gas up for you as you ride or sit in traffic. The 2 fuel tanks get plenty of heat off the engine and the fuel rails send back warm fuel to the tank. "Gas" can boil as low as 95f or 122f depending on who says so.

Table Definitions, Sources, and Explanatory Notes

.
"Motor gasoline, as defined in ASTM Specification D 4814 or Federal Specification VV-G-1690C, is characterized as having a boiling range of 122 to 158 degrees Fahrenheit at the 10 percent recovery point to 365 to 374 degrees Fahrenheit at the 90 percent recovery point."

 

[Larry Fine]

So, what is actually leaving the fuel when this happens?

 

[FieSTa45]

You might want to try a few tanks of ethanol free gas. The price point is not much different the 93 octane in my area.

 

[Ryan_B]

Mine "gurgles" in the heat (most noticeable when you shut it off in the garage), but not this boiling that you filmed. Mine is more of a 1 second release every 2-3 minutes. Then again, I don't open the gas tank when I hear it gurgle. Is the tank lid pressurized like a radiator? It would make sense if there were a couple psi on the gas cap, which would raise the boiling point quite a bit in the tank, maybe there is a bad seal is out on the gas cap?

Keep in mind, mine only has ~7000 miles. So, I have very limited experience. I have ridden in some of the hottest days we have had in this area though, I think I would have noticed a boiling tank.

Thank you,
Ryan

 

[Andrew Shadow]

Mine is more of a 1 second release every 2-3 minutes.

Probably because the cap is on and it on gurgles when the pressure gets to the point that it is released by the cap. If you removed the cap, you may well see the same thing that Raymond posted.

 

[MidLife]

Probably because the cap is on and it on gurgles when the pressure gets to the point that it is released by the cap. If you removed the cap, you may well see the same thing that Raymond posted.

Do you think it could be related to the Evap Canister Purge Valve closing when shutting off the engine and somehow causing vapors back to the tank as the tank pressure dips? I don't know enough about it to tell.

Smog Canister Question | ST1300 Related

Got an ST in the garage with a melted smog canister line. The line is the large one that comes straight out of the bottom of the can, and is called "canister air suction hose". It should exit the bottom of the canister, route along the frame, behind the engine, and come to rest in the metal...

www.st-owners.com

 

[RichKat]

According to Google, gasoline can boil at 95° F and Ethanol is 173° F, so I guess when I opened the cap,letting pressure off, the gasoline might actually boil. (I find that hard to believe, especially when you consider it was 114° F in Texas last month.) So I guess that would make my ethanol/ gasoline ratio even higher, gotta love the stupid politicians that came up with the idea of putting ethanol in our gasoline.

 

[Andrew Shadow]

Do you think it could be related to the Evap Canister Purge Valve closing when shutting off the engine and somehow causing vapors back to the tank as the tank pressure dips? I don't know enough about it to tell.

Smog Canister Question | ST1300 Related

Got an ST in the garage with a melted smog canister line. The line is the large one that comes straight out of the bottom of the can, and is called "canister air suction hose". It should exit the bottom of the canister, route along the frame, behind the engine, and come to rest in the metal...

www.st-owners.com

I really don't know, I never paid much attention to it or gave it much thought. I think that the fuel is sitting above a really big heat source. The fuel gets hot and it gurgles and burps the same as other liquids sometimes do before they get to a boil.

I wouldn't be surprised if it does it when the engine is running if it gets hot enough, we just can't hear it.

 

[MidLife]

According to Google, gasoline can boil at 95° F and Ethanol is 173° F, so I guess when I opened the cap,letting pressure off, the gasoline might actually boil. (I find that hard to believe, especially when you consider it was 114° F in Texas last month.) So I guess that would make my ethanol/ gasoline ratio even higher, gotta love the stupid politicians that came up with the idea of putting ethanol in our gasoline.

Gasoline is not like water with one well defined boiling temp. It is a mixture of over 100 hydrocarbons with each its own evap temp.

boiling points of fuels.mov

www.youtube.com

First will start evaporating around 100F and last at around 400F.

So what @jfheath has said makes a lot of sense.

.....I don't think that the fuel that you can see in the tank is boiling. I think the disturbance is caused by hot fuel vapours being vented into the tank, and the bubbles disturb the fuel that you can see.

One issue we have in Tx is that we are still switching to the more volatile winter gasoline blend as early as September, despite September temps being higher than they used to, per @RichKat , up to a summery 114 F this year.

So you might see bubbling from the evaporation of the more volatile winter gasoline components until the temp dips a bit more into actual winter territory (if it ever gets there...).

 

[jfheath]

114F Does not compute. Way beyond my acceptable operating limits!

Strewth. That's hot. I need some symbols:

-11C < my answer < 30C

 

[Al st1100]

canister purge valves are normally closed. Engine off this valve would be closed. If the purge valve was stuck open there would be a hard to start/ longer crank time after refueling and or other issues.

 

[MidLife]

Riding home from work, stop and get some chicken for dinner, head home and Moby starts running BAD, .....

Try brisket next time?

 

[core-aggie]

114F Does not compute. Way beyond my ...

Those extreme hot days are gone now, and have been for a short while.

I'd even question "114°" ... that might be "feels like", unless you're in the extreme heat regions.
(example below, though we're not in Houston)

Houston September 2023 Historical Weather Data (United States) - Weather Spark

weatherspark.com

 

[MidLife]

Those extreme hot days are gone now, and have been for a short while.

This Sep was hottest on record in Houston. Maybe time to consider switching to the volatile winter blend later, maybe end of Oct like in CA, to prevent some to be scared by their ST gargles (not popular though, as summer blend is more expensive).

 

[Cogmeister]

114F Does not compute. Way beyond my acceptable operating limits!

Gas mark 2 round here
46Celcius

 

[RichKat]

I'd even question "114°" ... that might be "feels like", unless you're in the extreme heat regions.

114° was actual temperature
Feels like was 116°
Welcome to Texas