Gas tank blowed up !

Catmandu2

Catmandu2

Joined
Sep 22, 2015
Messages
97
Location
Wasaga Beach, Ont. Canada
Bike
'04 ST1300 Blue STar
It blowed up real good !! Forgive me,,, that's an old comedy line from the Second City comedy group. But my upper gas tank did blow up (inflated like a party balloon),, which I think is fair to say,, that's pretty uncommon. It is now 5 inches wider,,, and about 2 inches thicker,, so destroyed,,, and will only make a pretty wall piece,,, for the bike barn. First,,, I want to thank Gordow,,, for helping me get a great replacement. His 2006 black tank is a drop in fit,,, for my 2012,, despite the different joiner elbow hose. I also replaced the evap cannister,,, which I think will prove to be root cause. So how did this happen,,, well,, this bike,, ThunderSTruck, is 14 years old,, and I have been riding it for 5 years. I have always noticed that it built a bit of pressure in the tank/s,,, compared to my 2004,, which never has any pressure. But all our articles and video's on the issue (fish bubbling in the tank,, etc) opined that, as long as the bike is running fine,,, it's just a peculiar charactoristic of some of our st13's. Well,,, that changed as I rode home,, in hot 34c weather,, and after 60 minutes riding,, and cruising through a 60kph reduced speed zone,,,, POW,,, the tank tried to leave bike !! Considerable force was generated at whatever pressure was in the tank over the large area's of the upper and lower tank shells. The lower rear tank sections (by my knees) flared out 2.5 inches on each side. The lower tank shell "oil canned) down a couple of inches in various places,,, jacking the tank up against the intake box,,, and tearing the front mounting bracket nearly off. There was a large release of gas fumes,, but I got the bike stopped and shut down pretty quickly. As I realized there was obviously elevated tank pressure Opening the gas cap allowed a huge amount of pressure out. But the bike was running fine,,, despite blowing up,,, LOL,,, so I caught my breath,,, and it started up fine, and rode another 10 minutes to home. That's where I noticed how badly the side fairings were distorted. Once I had it apart,,, I knew the tank was toast,,, and after a short search,,, found the ideal candidate with Gordow. So this was pretty exciting,,, having the tank blow up,, between you legs,, at speed. Good thing it doesn't happen every day,,, cause the tank is an expensive item to replace !! ThunderSTruck is back in service now,,, running great,,, and exhibiting zero pressure in the tank/s. At some point,, I will bandsaw the evap cannister open,,, as one of it's ports seems a bit flow restricted. btw,,, I did test the evap solonoid/valve,,, and it functions normally, and it's still in the bike. So I just wanted to relate my experience with all this too any other owners who are getting a bit of pressure in the tank/s,,, and like me,,, accepted that as manageable. Cheers,,, CAt'

20260519_222212.jpg20260601_201605.jpg
 
Catmandu2 said:
It blowed up real good !! Forgive me,,, that's an old comedy line from the Second City comedy group. But my upper gas tank did blow up (inflated like a party balloon),, which I think is fair to say,, that's pretty uncommon. It is now 5 inches wider,,, and about 2 inches thicker,, so destroyed,,, and will only make a pretty wall piece,,, for the bike barn. First,,, I want to thank Gordow,,, for helping me get a great replacement. His 2006 black tank is a drop in fit,,, for my 2012,, despite the different joiner elbow hose. I also replaced the evap cannister,,, which I think will prove to be root cause. So how did this happen,,, well,, this bike,, ThunderSTruck, is 14 years old,, and I have been riding it for 5 years. I have always noticed that it built a bit of pressure in the tank/s,,, compared to my 2004,, which never has any pressure. But all our articles and video's on the issue (fish bubbling in the tank,, etc) opined that, as long as the bike is running fine,,, it's just a peculiar charactoristic of some of our st13's. Well,,, that changed as I rode home,, in hot 34c weather,, and after 60 minutes riding,, and cruising through a 60kph reduced speed zone,,,, POW,,, the tank tried to leave bike !! Considerable force was generated at whatever pressure was in the tank over the large area's of the upper and lower tank shells. The lower rear tank sections (by my knees) flared out 2.5 inches on each side. The lower tank shell "oil canned) down a couple of inches in various places,,, jacking the tank up against the intake box,,, and tearing the front mounting bracket nearly off. There was a large release of gas fumes,, but I got the bike stopped and shut down pretty quickly. As I realized there was obviously elevated tank pressure Opening the gas cap allowed a huge amount of pressure out. But the bike was running fine,,, despite blowing up,,, LOL,,, so I caught my breath,,, and it started up fine, and rode another 10 minutes to home. That's where I noticed how badly the side fairings were distorted. Once I had it apart,,, I knew the tank was toast,,, and after a short search,,, found the ideal candidate with Gordow. So this was pretty exciting,,, having the tank blow up,, between you legs,, at speed. Good thing it doesn't happen every day,,, cause the tank is an expensive item to replace !! ThunderSTruck is back in service now,,, running great,,, and exhibiting zero pressure in the tank/s. At some point,, I will bandsaw the evap cannister open,,, as one of it's ports seems a bit flow restricted. btw,,, I did test the evap solonoid/valve,,, and it functions normally, and it's still in the bike. So I just wanted to relate my experience with all this too any other owners who are getting a bit of pressure in the tank/s,,, and like me,,, accepted that as manageable. Cheers,,, CAt'

20260519_222212.jpg20260601_201605.jpg
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Glad you have ThunderStruck back together and still moving. Glad I was able to help you out. Gordon
 
TerryS said:
Sounds like you have created the mythical ST1300 "Extended Range" with a now 40L gas tank!
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Right,,, Terry,, got to look on the bright side !! CAt'
Andrew Shadow said:
That must have been exciting!

I would be inclined to have a look at the fuel cap as well. Regardless of a failure elsewhere the cap is supposed to release excess fuel tank pressure
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Yes,,, that actually did happened,, Andrew,,, as I described there was an initial release of gasoline vapors when I was moving. That would have been when the pressure overcame the caps seal. But that reduced the pressure so that the cap was able to reseal,,, and of course by the time I stopped the bike and got my ignition key into the cap, and opened it finally releasing the remaining pressure. Peak pressure would also have been reduced as a result of the tank expanding. It was a pretty chaotic event,,, over in 10 to 15 seconds,, estimated,,, including stopping the bike from roadspeed. It's not the type of thing that one trains for,,, lol,,, CAt'
 
Andrew Shadow said:
That must have been exciting!

I would be inclined to have a look at the fuel cap as well. Regardless of a failure elsewhere the cap is supposed to release excess fuel tank pressure is it not?
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see post #6,, Andrew,,, somehow I got my replies mixed up. I inspected my cap, before installing it in the replacement tank,,, and it operates normally. For those who wonder,,, there is no vent in the cap. The ST13's evap system is mostly sealed while the bike is running and vapor is sucked up into the throttle bodies. Once the bike is shut off,, the vapors are stored in the evap charcoal cannister,,, until they can be drawn off on the next start. I understand it meets a California emission spec. cheers, CAt'
 
Andrew Shadow said:
I wasn't referring to the fuel cap seal. The fuel cap has a two-way valve in it to relieve both pressure and vacuum as/if required.
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hmmm,,, I didn't see that,,, but there are two square holes on the bottom of the cap,,, and both are outside the cap seal. I did try to move air in both directions thru those holes in the caps on both my bikes,,, but neither flowed. The 2004 has never had a tank pressure problem. And, the 2012 doesn't have one now,,, and there have not been any changes to the caps. CAt'

ps: maybe the initial blow off was thru the 2 way valve that you mention ??
 
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Thanks for this. Something else I will now worry about every time I hear a tank gurgle. ;)

But seriously, glad you are okay and glad it didn't rupture. I can't remember who had a fire from a cracked tank-to-tank rubber hose, but ever since I saw that I carry a fire extinguisher on the back rack just in case.

Ryan
 
Catmandu2 said:
hmmm,,, I didn't see that,,, but there are two square holes on the bottom of the cap,,, and both are outside the cap seal. I did try to move air in both directions thru those holes in the caps on both my bikes,,, but neither flowed. The 2004 has never had a tank pressure problem. And, the 2012 doesn't have one now,,, and there have not been any changes to the caps. CAt'

ps: maybe the initial blow off was thru the 2 way valve that you mention ??
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It seems strange that the only fuel tank vent is through the charcoal canister. Normally there is a valve in a fuel system that vents excess pressure and relieves excess vacuum as required. On motorcycles that valve is normally located in the fuel cap as it needs to be at the highest point of the fuel tank to prevent venting liquid fuel. I just assumed that there was such a valve in the ST1300 fuel cap but quite honestly I have never bothered to check to see if that is so.
 
Because of evaporative emissions restrictions, I don’t think there are any vents in a modern (bikes or cars) fuel system that directly vents to the atmosphere. Any venting must be scrubbed through the vapor canister.
 
Catmandu2 said:
see post #6,, Andrew,,, somehow I got my replies mixed up. I inspected my cap, before installing it in the replacement tank,,, and it operates normally. For those who wonder,,, there is no vent in the cap. The ST13's evap system is mostly sealed while the bike is running and vapor is sucked up into the throttle bodies. Once the bike is shut off,, the vapors are stored in the evap charcoal cannister,,, until they can be drawn off on the next start. I understand it meets a California emission spec. cheers, CAt'
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There should be a purge solenoid that controls how much and when it draws vapors. Purge solenoid could be stuck closed or the vacuum hose is pinched. I guess it's possible the sack in the canister be coming apart and charcoal is plugging lines up.

1781151068530.png
 
Al st1100 said:
There should be a purge solenoid that controls how much and when it draws vapors. Purge solenoid could be stuck closed or the vacuum hose is pinched. I guess it's possible the sack in the canister be coming apart and charcoal is plugging lines up.

1781151068530.png
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I tested the purge valve,,, and it seemed fine. It's back in the bike now,,, and everything seems to be working like a charm now. Believe me,,, I am checking for pressure multiple times,, before, during and after each ride. I verified that all the hoses were flowing as well. Normal operation of the purge valve is closed when the bike is off,, and open when the bike is running,, which allows collected vapors to be drawn off and up to the throttle bodies. The only component (other than the tank) that has been replaced, is the evap cannister. There is one port on the original evap can that seems partially restricted,,, so I am thinking that may be the problem zone. This over pressure occurred when the bike was running,,, and therefore the purge valve would have open as well. I'll try to check tomorrow,,, to see if that restricted port on the cannister,, is where vapor flows into the purge valve. I did notice how heavily built the evap cannister is,,,, cheers,, CAt'
 
I'd be converting that bike to non-Cali spec, ditching the cannister/solenoid and running the vent and overflow hoses down to atmosphere as most non-Cali bikes are.....

However, it is true cannisters are being added to modern bikes.
 
wjbertrand said:
Because of evaporative emissions restrictions, I don’t think there are any vents in a modern (bikes or cars) fuel system that directly vents to the atmosphere. Any venting must be scrubbed through the vapor canister.
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I think you are right. Otherwise why would so many cars' gas tanks 'whoosh' when we pull the cap to fuel up. The vapor canister is not supposed to be airtight, once the fuel vapor goes through the activated carbon it exits through a vent.
 
Catmandu2 said:
I tested the purge valve,,, and it seemed fine. It's back in the bike now,,, and everything seems to be working like a charm now. Believe me,,, I am checking for pressure multiple times,, before, during and after each ride. I verified that all the hoses were flowing as well. Normal operation of the purge valve is closed when the bike is off,, and open when the bike is running,, which allows collected vapors to be drawn off and up to the throttle bodies. The only component (other than the tank) that has been replaced, is the evap cannister. There is one port on the original evap can that seems partially restricted,,, so I am thinking that may be the problem zone. This over pressure occurred when the bike was running,,, and therefore the purge valve would have open as well. I'll try to check tomorrow,,, to see if that restricted port on the cannister,, is where vapor flows into the purge valve. I did notice how heavily built the evap cannister is,,,, cheers,, CAt'
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yes the canister is built heavily but inside is coal with a lining that can rarely disintegrate. I would check all the hoses, the vent hose and the hose that goes to the gas tank. When the bike is shut off the fuel system is sealed, heat from the engine will cause the gas to expand and pressurize the fuel tank. If the pressure becomes too excessive the gas cap should vent.

1781182669218.pngbasic canister.
 
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I don't think any of the fuel caps have an air vent except for the ST1100. Other than the 1100, the air vent is a tube that connects through the bottom of the tank and rises internally to very near the roof. That should allow air to enter as the fuel is consumed, or for vapours to exit when the temperature rises. I know that you can happily set a fuel tank on its back like a turtle and not lose a drop for weeks, and I have done that with my VFR800s and VFR1200. I confess that I am amazed that the rubber connecting hose between the upper and lower tanks wasn't the failure point bu maybe that is a reinforced hose with a really high burst pressure. In this instance, the lack of free venting through the canister has to be the smoking gun, sort of suprised that this also didn't cause running issues due to poor fuel flow as the same blockage would cause a vacuum in the fuel tank.
 
RaYzerman said:
I'd be converting that bike to non-Cali spec, ditching the cannister/solenoid and running the vent and overflow hoses down to atmosphere as most non-Cali bikes are.....

However, it is true cannisters are being added to modern bikes.
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I don’t think Honda ever built a 49 state non-California model. All ST1300s were CARB compliant.
 
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