Modern Vespa

Sounds like he just blocked the return hose. Which is correct.

Yes, that one is plugged, and the overflow hose is not (but the roll-over valve is in line).

So far no more smells, but I need to get the tank level lower, so more gas volume can build up and push. That's the scenario where I had most of my smells in the past.

That makes sense - a smaller volume of liquid in the tank will heat up faster over the hot (but cooling exhaust) - and presumably will push fumes into the canister earlier and with more pressure.

I think the saturated canister is the answer - well found if so.

As far as I am concerned, this case is closed. Thank you all for your lively collaboration and the long list of suggestions. I recap:

* the tank may be leanking
* replace all hoses
* remove the carbon cartridge
* don't fuel up before getting home
* don't replace the fuel lines
* temporarily disconnect the evap
* don't disconnect the evap
* drill a hole in the gas cap
* do not drill a hole in the gas cap
* remove evap canister and both valves.

And the winner is...................................not listed. The winner is to replace the evap canister with a new one. ETA: XLR8 had the correct idea that it might have been saturated.

I just came back from a long WOT ride with 1/3 full tank. Lots of farting, like every two to three seconds. With that much gas passing, the stink could be worse than it is, but it is there, no doubt.

A glance at the end of the overflow hose shows a bit of wet inside, so fuel fumes are definitely evaporating in there, and without the canister, they come straight into the garage. So, a new canister will be ordered and installed, for the next 30+k miles.

Meaning?

Done with you on this bro. Good luck with the evap canister change. Hope it is everything you dreamed.

Jim, how long should I expect this fuel expansion thing to take effect? So far, within 15 minutes after a hot ride, the level has not moved one cm, I keep having 13 cm of air space above fuel level.

Okay, I think my experiment is now finished.

I came back from a ~40 minute ride, of which the last 15 were at WOT on the freeway. Just off the FWY -- the tank being down to two bars now -- I refueled to the first click, like I always do. Home is about one mile from the gas station.

At home, I measured the air space between fuel level and filler neck:

It was 13 cm at time zero
still 13 cm 15 minutes later
12.8 cm 35 minutes in
12.5 cm 47 minutes in. The exhaust was then only hand warm, so I don't expect much more, if any, expansion.

I think this debunks that myth.

This has been the most helpful thread on MV for the past week. Since the case is closed I think it appropriate to express my appreciation to Salima and Arno as well as all who contributed to its development. Thank you.

Max, I am glad you are seeing it that way, thank you. Just hold out a little longer until I get my new canister and can confirm that it actually did solve the problem (which I believe but can't know for sure).

For anyone who is following this thread, it is highly probable that Arno had a "saturated canister":Not a "clogged canister".

The scooter has a lot of miles on it and over a period of time, the canister can become saturated due to overfilling and/or just absorbing fumes. I believe that his GTS is an 07 or 06 model with a lot of mileage so it's had a lot of use.

Fingers crossed for you buddy!

And the thread goes on ...

Jack, if clogging comes mainly from overfilling, than I would agree with your assumption. During the six years I've had it now, I may have overfilled five or six times, and when it happened, I did all I could to quickly lower the gas level below the little hole.

It is an early 2007 model.

Arno, I don't think that you have a clogged canister. I think that you have a "saturated canister" that has simply become saturated due to some overfills but primarily due to the amount of fumes that have been drawn through the canister over 40,000 plus miles of use. Remember that the hose that goes from the overflow line to the canister is constantly passing fumes from the gas tank through the canister and then passing those fumes to the throttle body. After you pass enough fumes from the gas tank plus any overfills through the charcoal in the canister, it will eventually become saturated and the charcoal will no longer mask the smell of gasoline. From doing some Googling about this subject in automobiles, this also happens to their evap systems and the solution is to replace the canister. I mentioned this in this thread in an earlier post (or two). I am 99.9% sure that your problem was a saturated canister.

I am loading the gun and putting it to my temple right now...click...damn I was hoping for the end to this insanity.

Bwaaaaaaaaaaaaaaaa haaaaaaaaaaaaaaaaaa haaaaaaaaaaaaaa

Unsubscribe?

So, given the reason you want to keep the evac system is environmental responsibility and also assuming the the problem is a saturated canister, how are you going to dispose of the saturated canister? Is the disposal method going to be any better for the environment than venting the fumes to the atmosphere in the first place? Please include the environmental impact of the manufacture of the charcoal canister (original and replacement) in your analysis.

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Healthy unscented farts. Only you, Arno!

I don't think it is unreasonable to place this thread in context when answering the question - there has been previous discussion on keeping the evap system and your reasons for wanting to do it. Fair enough. The most likely cause of the fumes was identified by the forum was identified as the evap. It looks like that advice probably identified the issue.

This thread and the related ones by you and Arno indicate that you have two issues. One is fumes, two is environmental responsibility. I actually admire that and have similar environmental sensibilities. My point was to look at the total impact of keeping the system in place. If it meets your goals of less environmental impact, fine. If your actions of keeping the evap system in place have more impact than disabling it, have you really met your goal?

My statement was not attack, judgement, support or ridicule. It was a recognition that disposing of a contaminated canister is an environmental issue (you were not going to simply put it in the trash), as is the resources required to manufacture the canister.

What you do is ultimately your decision, but if you are going to make a decision, at least make it an informed one.

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I am wondering if the air filter may have somehow become saturated with fuel. How long since you have inspected the air filter? I may be wrong in my thinking but it is the first thing that came to mind. I hope you all get it figured out.

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Almost all...

I've gotten around (no, the weather allowed me) to install the new canister yesterday. I took the opportunity to make it a Wiki article.

Everything runs nicely (no change there) and I have to go for a longer ride so my tank runs lower and the engine is nice and red hot-that is when I usually got the fuel stink. Today looks like a rainy day, so it will be Monday or Tuesday before I do it. That, I expect, will be the (happy) end of this story.

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After a fast 100 mile ride and arriving with a near-empty tank, it was time to prove or disprove the success of this endeavor. About one minute after parking it back in the garage, the farts started, and they......(drumroll)....did not smell anymore. So everything is back in working order again.

The only part that was replaced was the evap canister. None of the valves, and no hoses. That means, there was no leak causing the fumes, only a saturated canister. Voilà.

What I saw along the ride today:


ETA: Deer Creek Reservoir and Wasatch peaks in the background

It's good to hear that you have found the source of the gasoline smell. Enjoy!

I for one am relieved that you found the source of your problem. Now I am wondering why my scooter (and probably most of the world's scooters outside the US of emissions control of A) that doesn't have an evap canister installed doesn't have a problem with gas fumes in the garage. Must be a defect. I will investigate.

And how did you dispose of the saturated canister?

Am I smelling a whiff of sarcasm in your lines ? But seriously, I have long been asking myself the same question, and the only answer I can come up with, (of course), is that I am cursed with an oversensitive nose (and so is Salima). Or most of these scooters are not parked in garages but outside, where the fumes disperse quickly. I don't want to suggest that the garages that also are home to one of those scooters might always be having some fuel in the air, so it is not noticed. No, if I suggested that, I'd be stoned...

You never know bra. You never know.

What you were smelling were the fumes from the saturated canister. Once totally saturated (and yours was), it was going to continue to stink because the charcoal crystals had absorbed so many fumes that they smelled like gasoline. A scooter with no canister wouldn't smell because the fumes emanating from the overflow line are so miniscule that you wouldn't smell them. That's why I told you in both of your threads that your problem was the canister.

According to code of local auto service industry. Why, did you want it?

Most of you probably know this already, but I didn't:
According to my experienced Vespa and Mazda service writer, these charcoal canisters live forever if one never overfills. With each overfill their charcoal chunks disintegrate some, and when they have all disintegrated, they are toast and the canister needs to be replaced.

A well-calibrated pump provided, overfills can be avoided safely by ending the refuel process after the first click of the nozzle. With California's vapor caption devices, this will not reliably work on scooters.

No, just curious, though my curiosity is not satiated with 'according to code'. What does your code say?

The proper protocol, as confirmed by our long-time Vespa and Mazda dealer, is to discard it into the regular waste management system. Special treatment is explicitly not required. The rationale behind this possibly surprising answer is that the canister is a strong, almost fully enclosed shell that safely holds the charcoal mush in which the remaining fuel content is bound.

As Salima had mentioned earlier, we do the best we can with the information we are given.