Gas Erupts from Tank

[fjrchooser]

Guess I'll have to check the orange grommet again when I'm near the bike again.

However, in both my geysers, nothing happened until I added cool gas from the pump to the boiling gas in the tank. The tank cap was wide open for several seconds to over 2 minutes before my geysers allowing plenty of time for any pressure to equalize. Other than the boiling fuel - picture a pot of water at full boil, thats what I saw looking into the tank both times- I don't see where a pressurized tank comes into to this phenom. Nothing but a chuff on opening, an nothing more would have happened had I not added fuel while it was still boiling.

Silver Penguin, I've got no idea if the formulations that change octane also change vapor pressures/boiling points enough for 85 to do this at altitude when 87 hasn't. Could be coincidence that I've only run into it with the 85. Of course ,other than Nebraska I've also been at altitude simultaneous with the 85 usage & geysers. No geysers in Nebraska and I'm sure it was hotter there too but don't recall the gas boiling like it did in the mountains.

Perhaps a combination of the tank overpressurizing (orange grommet?) and lowered atmospheric pressure reacting with the 85 formulation ? Like carbonation being released ? Maybe 87 would have done this too at the time, I dunno.

My avoidance in the meantime will be to re-check the venting and not re-fueling until the tank stops boiling.

 

[SkooterG]

However, in both my geysers, nothing happened until I added cool gas from the pump to the boiling gas in the tank. The tank cap was wide open for several seconds to over 2 minutes before my geysers allowing plenty of time for any pressure to equalize. Other than the boiling fuel - picture a pot of water at full boil, thats what I saw looking into the tank both times- I don't see where a pressurized tank comes into to this phenom. Nothing but a chuff on opening, an nothing more would have happened had I not added fuel while it was still boiling.

It's simple physics and HAS NOTHING TO DO WITH OCTANE!!!!!!

Ok, so for the simple physics in your case - BECAUSE OF THE ORANGE RUBBER GROMMET not allowing your tank to properly vent, there was a build up of pressure in your tank (which is why you heard the 'chuff'). Here's where the simple physics comes in - the increase in pressure in your tank raises the boiling point of the liquid (fuel) and allows the fuel to get much hotter (retain more heat) than it normally would if the tank properly vented. So now, when you release that pressure by opening the fuel cap, the boiling point is now lowered to normal but all that hotter than normal fuel holding all that heat is still there and begins boiling. And when you add any new fuel, due to all the heat in the tank and the fuel thats in the tank, it immediately begins boiling too, causing your geyser. Imagine what would happen if you poured a cup of water into a pan that is on the stove and heated to 400+ degrees? Same idea here.

So not only does a properly venting tank relieve any pressure or vacuum, but it also keeps things from building too much heat. Which is why normally, with a properly venting tank you don't see your gas boiling when you open the filler cap.

It's a pressure thing. Not a fuel thing.

 

[Constant Mesh]

I removed the gas cap this morning for a quick inspection. There is one drain hole/pipe at about the 10 o'clock position just outside the gas filler opening. If this is the overflow pipe/hose then I guess it's only value is to drain away any gas that might overflow beyond the tank opening during filling. Maybe it also drains any water that might get down in the recessed area around the cap assembly during a rain shower, etc.

Maybe the gas cap has a high pressure relief device and any gas that escapes can be drained away via the overflow pipe. The cap's gasket is spring-loaded so it's very likely a pressure build-up could raise the gasket up off the filler opening allowing hot vapors and possibly liquid to leave the tank. You can feel the gasket spring mechanism give a bit as you push down and close the cap.

 

[fjrchooser]

Thanks ScooterG, your explaination makes sense. I was a little baffled by the all-out-of-proportion intense reaction a little cool fuel made.

I'll include the cap test (Thanks Fred W. ! ) in future vent checks !

 

[Ignacio]

I think I just had this phenomenon happen to me a few weeks ago....although it didn't result in an actual geyser in my case. I've gotten the "chuff" effect at times before when I've opened the tank. It's usually in a nice hot 90+ day in the desert west after running down to reserve.

This case I got a particularly loud chuff sound as the tank depressurized. I could feel the blast on my hand of hot air and gas vapor subside after a second or so as the mostly empty tank normalized with the surrounding air. However, after about a second I could actually feel the air coming out of the hole increase in intensity AGAIN. I could also feel the tank rumbling as if the remaining gallon or so of gas was coming to a boil. This second event last maybe 3 or 4 seconds.

Again, it didn't turn into a geyser that actually came out of the tank, but after about 20 seconds I digested what had happened and figure it would have been a geyser event if I had more fuel in the tank.

Anyway, the notion that the sudden pressure drop allows the liquid to boil makes sense to me.

I do wonder if there's a gasoline chemistry component as well. In my case, I had fueled at a much lower elevation (like 2000') and refueled at 6000'. Maybe the elevation change outright...or maybe the formulation of the regional fueld for 2000 feet areas is at risk of boiling more than high elevation areas.....or maybe the batch had a higher vapor pressure than usual....or maybe since there's increasingly 10% ethanol in fuel it may be a factor.

Not much on Google I could find.....but I'll agree it's not people's imaginations.

 

[donaldb]

Yea.........

it'll also destroy your windshield as I have just found out! :angry:

 

[Fred W]

But here's the big question: Why the big pressurization?

 

[Ignacio]

But here's the big question: Why the big pressurization?

As in why is the fuel system of the FJR pressurized with a big spring? Or, is in why does the fuel become pressurized when it warms up?

The former has to do with emissions certainly...and so your fuel doesn't evaporate away while sitting.

The latter is an inherent property of fuel. It's expressed as the Reid Vapor Pressure and is actually limited by the EPA to the 7.8 to 9.0 PSI range.

 

[SkooterG]

But here's the big question: Why the big pressurization?

BECAUSE OF THE ORANGE RUBBER GROMMET!!!!!!

If I had a dollar.....

That orange rubber grommet is part of the path of tank ventilation. If it gets skewered then the tanky no venty and pressure builds up.

Iggy, I am willing to bet all that gasoline chemistry as nothing to do with it. Higher elevation will play a VERY small part in that the boiling point of liquids is lower at higher altitudes.

Things that would aid in building pressure if the orange rubber grommet is plugging ventilation:

1) Hot ambient temps

2) Low fuel level - less fuel to absorb heat.

3) Lots of stop-n-go riding which allows more heat to build.

4) Time - the more of it with the tank not venting, then the more heat and pressure allowed to build.

 

[Bogey907]

I just wonder why your football has a gas cap...

 

[Fred W]

But here's the big question: Why the big pressurization?

As in why is the fuel system of the FJR pressurized with a big spring? Or, is in why does the fuel become pressurized when it warms up?

The former. And it isn't pressurized with a big spring. The fuel vent goes through the gas cap, which mates with the orange rubber grommet, and on Cali models then goes to the charcoal canister. On non-Cali models after the orange grommet the line just goes down by the left foot-peg and vents to open air.

The only thing in a non-Cali model that would intentionally restrict venting is the pressure relief check valve built into the gas cap. But the pressure relief is supposed to relieve at a relatively low pressure. I can push air through mine with my mouth.

So, the high pressure you are getting, that is subsequently causing the gas to boil when it is suddenly released is not right. It is caused by some sort of blockage in the vent line. If yours is a Cali model the charcoal cannister may be FUBAR. If not, the orange rubber grommet may be messed up like Skooty said, OR the gas cap may not be releasing the pressure as it should.

I'm wondering how easy it would be for the relief valve in the cap to get messed up.

 

[Fred W]

I just wonder why your football has a gas cap...

How else do you get gas into it?

 

[Ignacio]

So, the high pressure you are getting, that is subsequently causing the gas to boil when it is suddenly released is not right. It is caused by some sort of blockage in the vent line. If yours is a Cali model the charcoal cannister may be FUBAR. If not, the orange rubber grommet may be messed up like Skooty said, OR the gas cap may not be releasing the pressure as it should.
I'm wondering how easy it would be for the relief valve in the cap to get messed up.

My vent lines are NOT blocked. I have confirmed both the line of the rubber grommet is not plugged as brake cleaner flows easily out on the ground as does the other vent line of the overflow area within the cap. And the grommet is intact, not pinched, and visually looks fine.

I believe my system is working fine in that when it's hot it will burp occasionally as pressure is built up to the point that the tank does need to vent. I've also had two caps and both seem to build up about the same amount of "chuff" when opened on a hot day.

Also, I don't have a Cali model.

As for the amount of pressure a tank builds up...I would suspect it's in or in excess of 9.0 PSI...as that tends to be the upper limit for vapor pressure allowed by the EPA. I would suspect they require manufacturers to have that as a minimum so we don't spew gasoline vapor into the air.

 

[paste007]

Yesterday, my Yamaha mechanic replaced the gas cap on my '06a. The unit would not rekey to match my ignition/saddlebag key, as it came with a shorter key, so now I've got two keys.

After removing the original cap, he blew out the exhaust line and I heard a pop. I questioned whether he'd blown off a tube or something, as nothing was evident on the ground. Either way, the initial test seems to show that this fix worked. He stated that Yamaha had agreed to replace the tank, if the gas cap fix did not work.

All work covered by YES.

Warranty work to date on my '06a:

--Replacement of console due to 17mpg reading on average gas consumption.

--Replacemennt of ECU.

--Replacement of ignition.

--Replacement of gas cap.

 

[Fred W]

I believe my system is working fine in that when it's hot it will burp occasionally as pressure is built up to the point that the tank does need to vent. I've also had two caps and both seem to build up about the same amount of "chuff" when opened on a hot day.
Also, I don't have a Cali model.

As for the amount of pressure a tank builds up...I would suspect it's in or in excess of 9.0 PSI...as that tends to be the upper limit for vapor pressure allowed by the EPA. I would suspect they require manufacturers to have that as a minimum so we don't spew gasoline vapor into the air.

Sorry, I never did reply to this.

I am not sure what amount of pressure buildup is acceptable, or intended, or what the pressure relief valve in the gas cap is supposed to relieve at. I did do some pretty thorough searching and reading of the factory service manuals, but I came up empty.

I do know that my '05 has never "chuffed" when opening the cap, even on the rare New England 100 degree days, in full sunlight, etc.. I've also never had boiling gas or a tank eruption, and my legs and bottom of my tank get the full 1st gen roaster treatment. That said, my lack of experience is hardly of any significance in the grand scheme.

I just wish we could determine what the engineers intended the tank pressure relief in the gas cap to be, as that could very likely resolve this whole dilemma.

Or if you didn't mind risking polluting the atmosphere you could just relieve the spring in the gas cap and see if the resolved your issue.

Personally, I think a few pints of raw liquid gas erupting out of the boiling tank and onto the ground is probably more hazardous to the environment than a little gas vapor being expelled out the vent line...

 

[Ice Man]

After initiating this discussion, I thought it best to update my experience. Yamaha paid to replace my gas cap -- they said the vent hole in the gas cap (just above the orange thingy) was blocked. FYI -- the new gas cap cannot be keyed same as ignition -- you end up with separate key for gas cap. I have experienced no further problems and this summer was hot as hell -- third hottest summer on record. The bottom line problem was the gas tank was not venting -- little vent hole in gas cap (not the little orange thingy, but the vent in the cap just above the orange collar) was blocked -- perhaps from washing the bike and dirt/yuk settled inside the little vent hole. Some have asked why would a vacuum result in gushing from the tank -- I suppose a tremendous vacuum results in a highly pressurized tank when vacuum is suddenlly relieved. Lesson learned: open the gas cap slooooowly. Good luck to all!!

 

[Pioneer007]

Vacuum pressure crushed my 07's tank due to it not being able to vent.

I found out today Yamaha will replace the tank and cap under warranty.

I also had the fuel splash/spray issue when opening the cap.

I dont look forward to using two keys.

linky

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[Geezer]

(snip) 


I dont look forward to using two keys.

I would be surprised if they could not install your existing lock in the new cap. Either that or have a locksmith reset the new lock to fit your key.

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