Modern Vespa

post deleted by Salima

I had a gas fume problem that took me till after the warantee ran out to solve... Turned out to be a defective fuel tank (a leak in the seam)... Had to do a risky soldering iron repair which turned out to be much easier than I expected and the problem is fixed.
look under the tail and see if the bottom of the tank has any wet spots... There shouldn't be any for any reason!

Also, look for brown or amber colored spots on the top of the engine, Which would be old fuel accumulation... Most of the fuel leaks will be on the top part of the engine... Oil leaks will be on the bottom.

We've done all them on mine and i think John changed his out on his GT and LX. Clear ones were bad but the others seemed alright. Couldn't hurt to do then all while your in there. The clamps that Piaggio put on some of them are a onetime use. Got our tubing from an auto store and the clamps from Lowe's. Good luck

After some prodding (=heating it up real nice ) I got it to fart, and the farts definitely come from the evap system.
I am not sure yet but have a hunch that the fuel smell comes from there as well. I will need some better hose to pin-point and sniff.

The two fuel lines from the tank to the injector look sound and tight.

So, how does one remove all those hoses and parts of the evap system? I can see a buckle around the canister. Undo that and pull? Or how?

FTR, I am planning to make necessary replacements there and fit it all back in in working condition.

All scoots fitted with the evap crap will fart. This is pressure releasing from the tank which is being heated by the hot exhaust. The farts will smell of gas eventually, but straight away if the cartridge has gas in it. It doesn't just take an overfill to do this - if you fill up within a few miles of home after a long ride, even stopping at the first 'click' and well away from the neck, then the cooling exhaust will still expand the gas in the tank and push a bit into the evap crap - or into the open breather on the rest-of-the-world scoots.

Try removing the carbon cartridge and drying that out first (just let any gas evaporate). Replacing the hoses will have no effect whatsoever - if you had a hose leak or blockage you'd have noticed by a dip in performance.

Also try not filling up just before stopping for a while. If you stop for lunch, fill up after lunch rather than before.

Removing the evap crap lets no more fumes into the environment (arguably less) - it's only there because of CARB regs that haven't been thought through for this type of vehicle.

Jim,
I had just filled up before I came home and checked again now for the fuel level: it is significantly (8-10 cm) below the overflow hole.
For at least the last 10 fills I am sure that I have not overfilled or that the fuel could have expanded to reach that hole. So, for quite a while no liquid fuel should have gotten into the canister.

Could it be saturated (or full to some extent) just from riding?
Where would the farts escape, from which part or port?

In the past, I have had farts after rides but no fuel smell. And I've had fuel smells without noticing any farts (but I did not verify that).

Just read the part re. disconnecting it and you'll see which hoses to disconnect so you can hook it back up when you choose to do so.

How to remove or disconnect the Evap Sys. from GTS/GTV

That's enough. Fuel expands quite a lot, and the fumes pushed out by the hot (yes hot, not just warm) gas will have gone into the evap crap and condensed. This fills the cartridge with liquid gas - which can linger in there long enough that there'll be enough left after the need to re-fuel again - and so on. I'm sure you didn't, as you're aware of a 'problem'. Wrong conclusion, it definitely could - even if just as fumes before condensing.

Just do not fuel up just before getting home. Fuel up at the start of the next journey.

My 250 used to fart after just about every ride but I don't ever notice it any longer for whatever reason and my evap system is still connected.

I've not yet bothered to remove the evap crap from our US scoots either. Once I'd worked out what the pitfalls were by leaving it in, we've just avoided them - by normally only fuelling up before riding, not after. Cannonball was an exception, but usually the fuelling-up would be at least half an hour after hotel arrival what with checking in, and having that essential first beer.

The first time any of those scoots gets an evap crap problem - it's going.

Arno's smelly problem ( ) is down to fuelling up at the end of a ride it would seem.

I hear you, Jim, but I think you are drawing the wrong conclusion now. When I park the GTS after a longer/faster ride in the garage (therefore out of the sun, if you know what that is ), there will be plenty of fumes inside the semi-filled tank, which will have warmed up already during the ride. So if they condense inside the canister, than that is where I get my smelly garage from.

Coming home with a full tank means that I just filled it with about 2 gallons of cool fuel, and to warm that all up to a point where it would expand would require some more and longer heat exposure, I believe.

That coincides with the fact that I typically (but not 100% consistently) get the fuel smells with a somewhat or more empty tank, not a full tank.

The tank is cold during a ride - the exhaust hardly heats it at all. Feel it as soon as you stop (the tank, not the exhaust!).

Then feel it 5, 10, 20 minutes later...

Hot petrol gives off loads of fumes. The tank is already under pressure (in US CARB evap-crap bikes) - those go straight to the cold cartridge, no other escape. 100F is considered cold in this scenario - the exhaust is over 400C, up to 600C inside the cat...

A near-empty tank will have more fumes inside, and then you have to consider how those gas fumes expand - my suspicion is that it's either just fumes for you or a partially liquid-filled cartridge. Take it out and smell it.

Vespas *will* fart in the US, smelly farts sometimes. They'll expel excess fumes elsewhere in the world to the open air. They will smell a bit with a fart or drip a tiddly bit of gas on the floor (depending on location) after a fast ride if you fill up before stopping for a while - even just long enough to pay a gas-station cashier when there' a queue. It's what they do. You'll have to change your habits, as the Vespa's is fixed. The fuel tank is right above the exhaust - the rest is inevitable.

I understand from previous threads you do not want to remove the evap system for environmental reasons (forgive me if this is a wrong assumption). It would appear to me that totally replacing the fuel lines if they don't need to be replaced will also have an environmental impact (the energy, resource and pollution/waste of manufacturing the parts). If jimc is right (and few would doubt his experience) and the fuel smell is the result of a poorly designed evap system to meet the emission standards, your proposed solution may leave you with the same resulting fumes plus the impact on the environment you were trying to avoid.

Perhaps your best option might be to temporarily disconnect the evap system. If the fumes problem stops, you have identified the problem and can then make a choice about the fumes/environmental trade off. You have also not wasted money and environmental resources on the new hoses.

If temporary disconnection does not stop the fumes then you have not really wasted much more than some of your own time and you can progress to troubleshooting another part of the system.

Cheers,

Chris

Whatever you do, don't disconnect the evap system. It couldn't possibly be that highly engineered system created solely for the smallest Vespa market in the world that's a problem.

Jim, again, I hear you regarding fuel expansion in a full tank. To put an end to this discussion, I will fill up my tank (up to the first click of the pump) after a longer ride just before I get home and then watch the fuel level in the tank every five or 10 minutes until I can touch the exhaust with my hand without getting burned. I will report back and hope that, whatever I find, will not be discarded as being anecdotal

Joedevola, you are making a valid point regarding the environmental impact of an unnecessary hose replacement. I had already put that on the back burner as all my rubber hoses feel very intact, flexible, without cracks. So I am now looking for leaks within the evap system.

Removing that system, however, and then allowing the fuel fumes from warm fuel to escape from the gas tank into the garage will, however, not only not solve my problem but exacerbate it by pretty much guaranteeing fuel smells every single time, while now it is only once in a while.

Thank you Xlr8 for the link, I think I know now how to get the parts removed so that I can inspect them and do what needs to be fixed, if anything.

What you are saying might be true. However, those of us in countries without the evap system don't appear to have this issue of fumes (this is an assumption - might be wrong). One of the experience troubleshooters here keeps pointing to evap, so it would appear to me to be a logical thing to try temporarily disconnecting. If nothing else, you will be able to ask for assistance with the statement 'have tried disconnecting evap system and it is not the issue' and not have the whole community telling you to remove the POS system

Oh, if you are going to view the fuel level after cool down of the scoot, you will be relieving the pressure in the system when you open the tank. This will effect the evap system as I understand it.

Question: when I refuel my car and unscrew the cap, I hear gas escape. So I assume it is a sealed system.

What are non-US Vespas like? Is there an overfill escape, like ours, with a hose just running down to the ground, or is it sealed and airtight, like my car?

If the latter, why should I not seal my tank and be done?

Drill a tiny pin-sized hole in the gas cap and you will never have to worry about the problem again. I promise you it works. Replacing the hoses will do nothing but waste your time and $.

I listened to my bike make stupid fart noises and stink up the garage for one day before I did the gas cap modification.

The hole is so small you wouldn't even notice it, but it works.

As I already said, replacing the hoses is off the table, so thank you for confirming this decision.

Your hole in the gas cap was called "a very bad idea" by some of the big wigs here. I think it had something to do with the scooter's rubber showing sideways. Good that it works for you. However, a question: when I park my hot scooter in the garage and the hot exhaust keeps warming up the tank, where will the fuel fumes go if not out that pinhole and into my garage? Or am I missing something?

The gasses never get built up and the tank vents all the time so there is no built up smells.

You never listen to any of our advice Arno and I wonder why you even ask for advice at all. I think it was JimC who all but begged you to disable the evap equipment last time you brought up this topic and you argued him the whole time. At the very least you could try my mod and get a new cap if you didn't like it. I live in the hottest place in the country and I know how gas fumes get in the heat and after a ride and what they do to a GTS.

A very good reason would be that the fuel system was not designed that way. If there was a fuel leak causing a problem, you would have even more gas smells in your garage!

The fuel system was, however, designed without the evap system. You have advice from a very credible source that this would be a likely source of the problem. However, for some unfathomable reason, you refuse to accept advice to that effect. This will lead others to agree with VEZPA's sentiments above

Interesting! Vezpa, as a matter of fact, I listen to ALL given advice. And then I take the liberty to think about it and discuss it before I blindly follow it all. If this hurts someone's feelings, then I am sorry about that.

At the end of the day, I will do what makes the most sense to me and I will report what happens, so we can all learn from it. I think that is fair.

DO NOT DO THIS! Unless you know your tank is vented that is. On some models (GP800 for instance) tanks are pressurised to some extent by design - they have a pressure release vale instead of an open vent. Plus drilling a hole is equivalent to just having a vent tube to ground instead of the evap crap - so not a solution for Arno/Salima.

My GTS' gascap came with this small vent "notch" cut into the inside allowing pressure out as it was designed. (11 o'clock position in this photo)

Our GT200L gascap doesn't have the cut out.

Sent from my iPhone

I have removed the evap canister and roll over valve from two scooters now and I never smell gas.

How does that notch aid venting? The sealing ring is still further into the cap...

And I'm pretty sure there isn't a different 'gas cap' made just for the US.

It lets the pressure out, slowly past the gasket, Otherwise whats its purpose and why the GTS and not GT200L.

Why wouldnt there be a separate gascap made for the US? Theres a separate entire evap.emissions control system made for the US.....

Good find about that notch difference in the fuel cap. Unfortunately, it has no effect on the GTS' seal, which is formed at the outer edge of the cap's gasket. See the image below. Also look at the filler pipe of the gas tank: there is nothing that would interact with this notch.

That said, our ingoing approach with this thread was wrong. It was going a palliative route, when I am really after a curative solution. So I need to find the etiology, to stay with medical terms.
My plan is now to remove the evap system and inspect all the parts and connections in hope to find the leak, fix that leak, and put it back together in working condition.

The advice I received here will be immeasurably helpful to achieve this goal. As I said, I will report on what I find and will keep asking and discussing, should there be further questions. Thank you for bearing with me.

Arno, I suspect that your canister has reached it's saturation point. You have a lot of miles on this scooter so it's absorbed lot's of fumes. Eventually, the charcoal in the canister becomes so saturated that it can no longer absorb the fumes and that's why you're smelling gas. JimC also makes a good point about filling up and then parking it soon thereafter. I don't think that you can revive the canister once it's reached a certain level of absorbancy so you'll probably have to buy a new one. If you remove the canister and it reeks of gas fumes, then you've found the problem since the purpose of the charcoal in the canister is to absorb all of the gas fumes. Good luck with tracking down the source quickly.

Oh. I was thinking about that canister and thought it works as a buffer, collecting fuel and also giving it back to the intake as it is breathed through. My thinking was that the charcoal might be losing its holding capacity with time but not that it is getting saturated with time. My plan is to weigh it once I took it out and then let it sit (and evaporate). After that, I will weigh it again to see if it lost any weight = fuel.

I doubt that you will notice any weight difference since this is not something that has just happened..........but an ongoing problem. The charcoal crystals can only absorb so much gas or fumes and will eventually lose their effectiveness. Of course, the crystals will last much longer when they just absorb fumes (with no gas entering) but when gasoline gets in the canister, it has to shorten the life expectancy of the charcoal.

May sound stupid but can't the filter be washed? Then dried out

If you do a Google search, you'll see that charcoal canisters in cars (they work the same way as the one in your scooter) DO get to the point of saturation, mainly due to gasoline contamination. The recommended fix is to replace the canister. I don't think that there's any way to clean the charcoal inside the canister although I found one site where someone cut open the canister and replaced the charcoal with new pellets. To me, that is ridiculous because of the time & effort, sourcing of the charcoal pellets, etc. You'd be much better off to just buy a new canister or leave it disconnected. The canister is nothing more than a filter and filters all eventually need replacement when they've run the course of their useful lives.

*BTW, Arno.............I found a lot of posts in car forums where the indication that the canister was bad was the strong smell of fuel emanating from the canister.

http://www.ehow.com/how_8104632_clean-charcoal-canister.html

I may be wrong but I think that if the system is working correctly the absorbed vapors are returned to the engine so in theory the charcoal should never need changing. Unless of course it gets clogged up from an overfill or something.

Sticky, I saw that page when I looked but found a bunch of others that said that overfilling with gasoline would eventually push the canister to the point where it should be replaced. I know that if you only overfill it a few times, a repair shop will typically attempt to dry it out but when you start getting a permanent smell of gasoline from the canister, my opinion is that it's time to replace the canister or remove the Evap system.

3 riding seasons and 5k miles later, 2 in the Florida heat with no issues = working solution. Taking the Evap crap off vents the tank anyway and many people here have done just that with no ill effect. I don't know where your argument on this comes from with this particular line of Vespa GTS machines.

First update:

I removed the complete evap system. All parts, hoses, connections looked intact, no sign of a leak anywhere. But the canister rieked of gas. I also noticed that it has a third opening with no hose attached. If the canister is somehow saturated or has reached its end of life, the smells could have come out of there. I don't know.

For testing, I put it all back together without the canister, and with a blocked hose to the engine. Runs fine. I heated it up really nice and then parked it in the garage. Farts healthily but doesn't smell.

Can I conclude safely that it is the canister that caused it?

PS: I have yet to test the fuel expansion with a full tank. Stay tuned.

Arno, if you hooked up the overflow hose back to the filler neck and the canister is now out of the system, is the overflow hose open or plugged? If you plugged it, it will cause pressure to build in the gas tank (not good) and will cause the engine to stall or stutter. i.e., that hose needs to be open if it's no longer connected to the canister.

When I Googled for "carbon canisters". there were threads in car forums that talked about having the smell of gas coming from the canister being due to it being saturated and in those cases the poster replaced the canister. You can attempt to dry it out but I think that it's just reached it's useful life and that you need to replace it if you're going to keep the Evap system intact.

Throw the bloody canister away man
and stop mucking about