Gas Erupts from Tank

[Ice Man]

OK guys --thanks for the feedback After researach here is my premilinary resolution:

1. The problem is a vacuum problem and not a pressure issue

2.) The vent hoses to the gas tank are not the issue -- both vent feely -- no blockage

3.) Temp does not cause higher tank pressure -- as the burning of fuel causes a vacuum in the tank -- the tank has a vacuum issue and will imlpode if vacumm is not relieved. I had a new 1982 Audi that had this problem and it took two new gas tanks before this issue resolved.

4.) The gushing "sucking sound" is, in fact, a suction sound -- resulting in a an explosion of fuel from the gas tank -- too much air rushing into the tank causing a gushing of fuel from the tank -- this really has nothing to do with the air temp as we are only dealing with a 30 degree variance.

5.) The bottom line problem is not enough venting of the fuel tank -- never a problem in the first 12k miles for my 05. I have an appt with local Yamaha dealer to have this problem looked at (in addition to 12k service). We may find that the fuel cap vent (fuel filler cap) has a venting problem due to washing of the bike and any dust, debris being washed into the vent hole.

I discussed this problem with my dealer - who promised to discuss with Yamahal-- will know in a week what they suggest is the problem.

 

[Fred W]

OK guys --thanks for the feedback After researach here is my premilinary resolution:1. The problem is a vacuum problem and not a pressure issue

2.) The vent hoses to the gas tank are not the issue -- both vent feely -- no blockage

3.) Temp does not cause higher tank pressure -- as the burning of fuel causes a vacuum in the tank -- the tank has a vacuum issue and will imlpode if vacumm is not relieved. I had a new 1982 Audi that had this problem and it took two new gas tanks before this issue resolved.

4.) The gushing "sucking sound" is, in fact, a suction sound -- resulting in a an explosion of fuel from the gas tank -- too much air rushing into the tank causing a gushing of fuel from the tank -- this really has nothing to do with the air temp as we are only dealing with a 30 degree variance.

5.) The bottom line problem is not enough venting of the fuel tank -- never a problem in the first 12k miles for my 05. I have an appt with local Yamaha dealer to have this problem looked at (in addition to 12k service). We may find that the fuel cap vent (fuel filler cap) has a venting problem due to washing of the bike and any dust, debris being washed into the vent hole.

I discussed this problem with my dealer - who promised to discuss with Yamahal-- will know in a week what they suggest is the problem.

Be careful using the bike until you figure this out. There have been reports of people sucking big dents in their gas tanks when the vent is plugged.

As I reported in another post, the vent line can be perfectly clear, but the gas cap is a critical part of the venting, so check that. You should be able to get air to flow easy through the little vent hole that mates with the orange rubber seal. If not, your problem is in the cap.

But getting back to the theoretical gas geyser. Not tyhat this is important to your problem, but I don't see how relieving a vacuum in the tank would cause it to erupt...

 

[user 711]

I have an 05 FJR with about 12k miles. I went riding with 3 friends yesterday -- it was 60 degrees & I filled my tank at the local Shell station. At 125 miles into the ride, my friends needed gas so I decided to fill my tank as well -- still had half tank -- it was probably 85 to 90 degrees. When I opened the tank, there was a "giant sucking sound" quickly followed by a column of gas gushing out of the tank -- about 2 feet above the tank -- fortunately no fire. Everything about the morning had been normal and this has never happened before. I read about this problem with an FJR that had been filled at near sea level, was transported to higher elevation and upon opening the tank, same thing happened. My ride did not involve any significant elevation change -- only about a 25 to 30 degree change in air temp.
Anyone else experienced this problem?

P.S. I did a search and could not find any mention of this.

I had the same problem with my '05 at 18k miles. Strong vacuum making it difficult to open the gas cap when filling up. Never had gas gushing out of the tank, but I've seen vapor coming out, probably being displaced by the air going in. Brought it to the dealer, they said the vent hose was kinked, supposedly unkinked it but the problem continued.

Last summer I did a long freeway ride in 90 deg temperatures and at some point felt a "knock" that sounded like it came from below tht tank. Got home, took lifted the tank and sure enough, it was slightly collapsed on the bottom.

Brought it to the dealer again, and this time they found that my CA-spec FJR (I live in WA but bought the bike 2nd hand from a guy in CA) had a blocked charcoal cannister that pas preventing the tank from venting. I have a YES warranty on the FJR, and after a call to Yamaha got them to agree to replace the charcoal cannister AND tank :yahoo: .

If your FJR is a CA-spec one, I suggest checking the charcoal cannister.

 

[Ice Man]

No, not a CA bike. My FJR is at the dealership now -- the problem is venting -- the dealership talked with Yamaha and they agreed the gas cap vent is not working properly (everything else checked out ok) -- the gas cap is to be replaced. I trust the dealership -- they do good work. I think the real issue is determining where the venting problem is -- could be couple different locations -- gas cap, charcoal canister (for CA models), etc. I had a new 1982 Audi 4000 that required replacement of two gas tanks (they collapsed) before the dealer figured out where the venting problem was -- same issue here (although my tank is not collapsed) -- hope the gas cap is the problem. Thanks for all of the feedback.

 

[Fred W]

No, not a CA bike. My FJR is at the dealership now -- the problem is venting -- the dealership talked with Yamaha and they agreed the gas cap vent is not working properly (everything else checked out ok) -- the gas cap is to be replaced. I trust the dealership -- they do good work. I think the real issue is determining where the venting problem is -- could be couple different locations -- gas cap, charcoal canister (for CA models), etc. I had a new 1982 Audi 4000 that required replacement of two gas tanks (they collapsed) before the dealer figured out where the venting problem was -- same issue here (although my tank is not collapsed) -- hope the gas cap is the problem. Thanks for all of the feedback.

I think that looking closely at how the venting system works, the gas cap would be the most likely culprit in any of these circumstances. It seems to be the most restrictive piece in the vent line.

For those that are concerned, and you may be wise to check this or suffer the dreaded imploded tank syndrome, you can check that the cap is venting using a piece of rubber vacuum line. Pressing one end over the small hole in the edge of the cap (highlighted in the below picture) that mates up with the orange O-ring when the cap is closed. You should be able to easily blow air through that hole. That is the direction the air will go when relieving vacuum in the tank.

You will also find that it will be a bit harder to suck air through the cap (positive pressure relief) as there is some sort of a check/pressure relief valve inside the cap, ostensibly for evaporative emissions reasons.

You can also check that the vent line below the tank is not kinked or clogged by moving the end of your mouth hose to the rubber o-ring and blowing. Obviously the cap assembly would have to be installed as normal (on the tank), not in the removed state like it is in the picture. There are no check valves or orifices below so the flow should be free and easy in that direction.

 

[Silver Penguin]

I've read through all the posts here, and only understand a small amount of what was posted. Perhaps some wise person can explain, in simple terms, if my problem is the same as what was described.

My bike is a Gen I and runs hot. Last time I rode in very high temperatures, I actually got first degree burns on my thighs from the gas tank. That was through a pair of riding pants. My seating position is further forward than most though, because I'm so short. Anyway, that problem was addressed with a change of riding pants, and not extending the windshield (which changes the airflow).

This weekend, I rode a long way in some ridiculously hot temperatures. At two of the gas stops, there was a strange sound when I opened the gas cap, as though I had released some pressure. I let it sit for a moment then tried to put gas in. The pump would not release more than 0.1 gallons at a time, before clicking off. The same pump filled Andy's bike with no problem.

Towards the end of the journey, when the temp had dropped from 109 to the high seventies, there was no problem filling the tank normally.

Thoughts? ideas? suggestions? Should I just stay home when it's hot?

Jill

 

[Wolfhound]

First thing I thought of Jill is do you have a heat shield installed on or below your tank ?

 

[Silver Penguin]

First thing I thought of Jill is do you have a heat shield installed on or below your tank ?

Unless that's a stock item, no I don't. I'm the third owner of this bike and have done very little to it. I don't ride in extreme heat conditions very often, so this is a new problem.

Jill

 

[Fred W]

This weekend, I rode a long way in some ridiculously hot temperatures. At two of the gas stops, there was a strange sound when I opened the gas cap, as though I had released some pressure.

It would be good to know if it was really pressure being released or a vacuum. My bet is it's pressure since you say it's only happening in high heat.

I let it sit for a moment then tried to put gas in. The pump would not release more than 0.1 gallons at a time, before clicking off. The same pump filled Andy's bike with no problem.

Operator error?

I assume that Andy filled his own bike, maybe he angled the nozzle differently? I have met many gas pumps that are finicky and will release themselves prematurely ( :blush: ) unless you get the perfect angle of attack. I really do not believe the heat would have anything to do with the gas pump shutting off.

Towards the end of the journey, when the temp had dropped from 109 to the high seventies, there was no problem filling the tank normally.

Different gas station, less finicky pump?

Just some theories...

 

[donaldb]

This same issue happened to me for the first time back on 7/24/08. Me and 2 riding partners were headed from Custer, SD to Golden, CO for the NAFO event. We topped off our fuel and started heading southwest, down through eastern WY. It was a very hot day. We stopped in Cheyenne for fuel. Pulled up to the pump and while sitting on the bike, I unlocked the gas cap and fuel shot straight up about 2 feet, covering me and the bike. Scared the crap out of me. Was I was about to go up in flames??

Before I left on this trip I removed the gas cap and cleaned the accumulated dirt and sprayed break cleaner through the vent hole to make sure the vent was clear, everything was good. So, at the fuel stop in Cheyenne I bought another can of break cleaner, removed the cap and sprayed again...results were the same, vent tube clear. Was wondering if I somehow pinched to rubber grommet when I closed the cap at my previous fuel stop and somehow blocked the vent?????

I'll ck the vent hole on the cap this week and make sure it is clear. Funny thing is...........this problem has not resurfaced again. After the gas gyser I rode more than 1500 miles, various elevations through the rockeys, including Mount Evans 14,260' and in low temps from the 50's to as high as 105 in Dumas AR. on my return trip home. But, no more vacuum/vent problems.

This was not a pleasant experience, I hope it does not happen again. The dangers associated w/a hot engine, possible sparks, ignition sources all around, covered in gas.......not to mention potential damage to the tank if this issue maybe continued w/o opening when I did. The only reason I stopped for gas is riding partner needed fuel....I did not...I still had aprox. 1/2 tank remaining, but decided to gas up since we were there and not have to stop again before Golden.

 

[Fred W]

This same issue happened to me for the first time back on 7/24/08. Me and 2 riding partners were headed from Custer, SD to Golden, CO for the NAFO event. We topped off our fuel and started heading southwest, down through eastern WY. It was a very hot day. We stopped in Cheyenne for fuel. Pulled up to the pump and while sitting on the bike, I unlocked the gas cap and fuel shot straight up about 2 feet, covering me and the bike. Scared the crap out of me. Was I was about to go up in flames??
Before I left on this trip I removed the gas cap and cleaned the accumulated dirt and sprayed break cleaner through the vent hole to make sure the vent was clear, everything was good. So, at the fuel stop in Cheyenne I bought another can of break cleaner, removed the cap and sprayed again...results were the same, vent tube clear. Was wondering if I somehow pinched to rubber grommet when I closed the cap at my previous fuel stop and somehow blocked the vent?????

I'll ck the vent hole on the cap this week and make sure it is clear. Funny thing is...........this problem has not resurfaced again. After the gas gyser I rode more than 1500 miles, various elevations through the rockeys, including Mount Evans 14,260' and in low temps from the 50's to as high as 105 in Dumas AR. on my return trip home. But, no more vacuum/vent problems.

This was not a pleasant experience, I hope it does not happen again. The dangers associated w/a hot engine, possible sparks, ignition sources all around, covered in gas.......not to mention potential damage to the tank if this issue maybe continued w/o opening when I did. The only reason I stopped for gas is riding partner needed fuel....I did not...I still had aprox. 1/2 tank remaining, but decided to gas up since we were there and not have to stop again before Golden.

The other half of the venting (that you may not have checked) is the passage and check valve that is inside the cap itself.

 

[Geezer]

This weekend, I rode a long way in some ridiculously hot temperatures. At two of the gas stops, there was a strange sound when I opened the gas cap, as though I had released some pressure. I let it sit for a moment then tried to put gas in. The pump would not release more than 0.1 gallons at a time, before clicking off. The same pump filled Andy's bike with no problem.
Jill

I had the same experience on the way home from NAFO. I assumed the pump was bad and finally gave up after getting about 89 cents worth into the tank. The other pumps at that station were in use and it was too hot to wait so I rode about a quarter mile to a different station and filled up with no problem. Perhaps that one pump was adjusted to be a little more sensitive than the others.

I also have had first degree burns from the hot tank after a long ride on a very hot day. I keep planning to insulate under the tank but I haven't gotten to it yet.

 

[Silver Penguin]

It would be good to know if it was really pressure being released or a vacuum. My bet is it's pressure since you say it's only happening in high heat.

I believe it was pressure, because he told me last night that he also got a blow back of gas, as though there were a big air pocket in the tank. The nozzle was tried in all different positions, with no difference. Heck, I even offered to give it a try but by that point it became a male pride issue, so I left well alone.

Thanks for the suggestions Fred.

Jill

 

[radman]

EFI tanks don't, by function of the injection system, pressurize any more than carb feed tanks-Gen I's have a feed-return fuel cycle, Gen II's have a single feed built in return system, neither of which pressurize the tank as a matter of course. A full tank with a blocked vent will pressurize the tank initially due to engine and atmospheric heat expanding the fuel, as well as the fuel's light ends gassing out from heat and just being sloshed around. Depleting tanks will form an internal vacumn as fuel is used, some have collapsed as a result, the pump is quite powerful. Kal bikes have a closed vent system, whereby a solenoid (AFAIK, most systems work this way) opens upon startup, venting the charcoal canister (which stores tank fumes) into the intake tract. The system allows atmosphere into the tank, but does not allow fumes to escape except via the venting system. This brings up the problems associated with constant overfilling the tank of any vehicle using a closed vent system-raw fuel can get into the venting system, saturating the canister, and ruining it's ability to absorb fuel tank fumes. In any case, flushing the vent tube on the non-Kal FJR's at each oil change with brake cleaner should be done as a matter of fact. It's exposed end just forward of the swing arm has a bad habit of collecting road splooge, hence it's tendency to become blocked over time. It helps if an angle cut is made at the tip, with the angled opening facing rearward. The Kal versions may benefit from cleaning the canister intake (venting to atmosphere) tube for the same reasons-but I don't know that it's as vulnerable as non Kals to collection crud-depends on it's location.

Edit-I should note that new vehicles are running a slight neg pressure in the tank-a loose cap will set a code, as will fueling with the vehicle running. I don't believe any bikes are doing this-yet.

 

[SkooterG]

Except for the occasional blocked tube, all these problems stem from the little orange rubber grommet getting partially dis-lodged so that the tank is not properly venting. I have experienced both the pressurized tank with spurting fuel, and the vacuum tank where it was almost impossible to open the gas cap. Both are rare occurrences.

IT'S THE ORANGE RUBBER GROMMET!!!!

Jill, there is no way that any condition on the FJR could affect whether the gas nozzle was working. I have occasionally had difficulty with some station's nozzles also. It's the nozzle. It's not so much the angle, but some nozzles are real finnicky in how you have to raise the guard, or venting mechanism, to get it to work.

 

[fjrchooser]

I recently was in Co. , Durango area June 28th-14th. Had the same thing happen to me twice. Both times very hot days, at altitude. 1st time I had 1/2 a tank and filled because everyone else did. I noticed a big chuff on opening the filler, not unusual on a hot day. I did notice the tank felt a bit like it was vibrating as I supported the nozzle with my hand around the filler. As soon as gas was added the tank erupted into the gas gyser mentioned here. I added maybe a tenth but a half gallon shot out.

After I finished the gas pump pee pee dance with the gas nozzle at full hose extensionI peered into the tank and saw the remaining gas was roiling pretty good. Waited 30 seconds for it to subside a bit while casually glancing around to see if anyone saw my little dance number. Added another shot and again the tank erupted but not as spectacularly as the first time. Did several more fills while in the mountains without a repeat.

On the very hot way home, a very low tank, very hot engine and overly cautious credit card company had me inside the station explaining my presence in Co. rather than Michigan. 15 minutes later, satisfied I was allowed to fuel. Gas was boiling bigtime when I opened the tank, a bit of a chuff as it vented. Watched the gas bubble rapidily for a minute or two more then gave it a squirt when it seemed to slow to an acceptable amount. The station pump kicked off simultaneously with the gyser erupting and me doing another dance. Not a problem since as long as that tank isn't boiling.

I'll be adding the insulation to my tank this winter, going to miss the mild warmth it provided fall and spring but not worth risking a gas gyser on the really hot days. My vents were clear, checked before going on the trip and after the first gusher. Back home while doing an oil & diff fluid change it checked clear again.

I was using 85 octance both times rather than the typical 87 I run in Michigan, do you suppose that could make that kind of a difference ? I've driven further and harder on hotter days before and never observed the gas boil in the tank before .

I sure won't be adding any while its doing so again either.

 

[Constant Mesh]

The FJR fuel cap may have internal spring-loaded check valves similar to this RoadStar cap.

https://roadstarclinic.com/content/view/136/96/

Allows air to enter the tank via the cap as the level drops and a vacuum develops but stops fuel vapors from leaving.

My question: Where is the overflow pipe opening at the top of the tank? Why can't vapors leave the tank via the overflow pipe and hose?

Some have speculated that the breather hose can pick up dust and debris under the bike and transport it up into the area under the gas cap. If the orange grommet is making a proper seal why isn't the dust pulled into the tank via the check valves rather than appearing just below the cap around the opening to the tank?

 

[Silver Penguin]

I was using 85 octance both times rather than the typical 87 I run in Michigan, do you suppose that could make that kind of a difference ? I've driven further and harder on hotter days before and never observed the gas boil in the tank before .

When I ride alone, my FJR gets 85 octane but when I ride with my husband, we both get 91, since his BMW requires the higher octane stuff. By the time we've paid the ATM fee, it's about the same cost as it would be to fill both bikes separately. Do you think that makes a difference?

Jill

 

[SkooterG]

Octane has nothing to do with it.

IT'S THE ORANGE RUBBER GROMMETT!!!

 

[Fred W]

The FJR fuel cap may have internal spring-loaded check valves similar to this RoadStar cap.
https://roadstarclinic.com/content/view/136/96/

Allows air to enter the tank via the cap as the level drops and a vacuum develops but stops fuel vapors from leaving.

Yes, the FJR cap is similar. I have not (yet) taken mine apart, but I do know that functionally it is the same. The cap has some sort of a check valve in the vent path that easily allows air to pass into the tank, but restricts the flow out of the tank. You can test this by using a rubber hose and putting it over the tank hole in the side of the gas cap (see picture). You can then alternately suck and blow through the hose to test the cap. Of course you have to press the test hose against the cap, over the little hole to seal it off well.

My question: Where is the overflow pipe opening at the top of the tank? Why can't vapors leave the tank via the overflow pipe and hose?

The overflow drain is the square hole on the side of the tank. As you can see in the picture, it is isolated from the tank when the cap is closed.