More Stella Auto issues. Edit: one issue solved?

[caffeine65]

Earlier this week, my ECS light started blinking at me. I looked up the code someone posted on the LML UK forum, and it comes back as an O2 sensor issue. I've seen this type of thing in cars before. More of an annoyance than a serious problem. It doesn't (shouldn't) affect the operation of the vehicle or create any harm, but sheesh, there's less than 500 miles! I'll have the dealer take care of it when I get a chance to take it in.

So then late last night. I was out for a nice, backroads jaunt, and the Stella died on me not once, not twice, but SIX SEPARATE TIMES while I was underway! Six frickin' times I was tooling along, doing anywhere from 35 to 50 mph, running strong when, out of nowhere, the bike just stalls.

The routine became this: coast to the side of the road dead, turn off ignition, wait a few moments, try to restart - but it doesn't catch, wait a few more moments, try to restart, and the bike's running strong again. It was only when I was furthest from home that I finally realized it was going to keep doing this and I'd better head back. EDIT: I think I've solved this issue with some tinkering. See subsequent posts.

Now here's the punchline… during this time, I also discovered the bike has a short/loose connection/faulty wiring in the taillight. Drive over a bump, taillight goes out. Another bump, taillight comes back on. Not a good thing for driving pitch black country roads, and even worse when you're sitting dead along the side.

I checked out the bulb and it seems snug, but otherwise I'm clueless when it comes to electrics & wiring. So I guess I'm limited to daylight riding until I can get THAT seen to. Grrrrrr!

[EvilNerdLord]

sorry to hear about/ read about all the problems autos are having...I had high hopes for the wee beasties.

Not to sound heartless, I'm glad I didn't wait and got my shifty when I did...

sounds like that warranty will be getting quite a workout.

[misterbrackets]

The tailight issue could be a loose wire/connector in the headset (or behind the horncast). I'm guessing the wiring for this is the same as the 4T shifty. If so, it's a yellow wire according to the diagram on page 20:

http://www.modernbuddy.com/pdf/Stella_4 ... manual.pdf

I would get accustomed to taking off the headset/horncast anyway --- you'll inevitably have to a few times down the road. I've had a few electrical and mechanical issues with my 2012 4T - but so far have been able to fix everything myself with help from this forum, research etc. It's actually part of the fun for me (as long as I'm not kept from riding for TOO long)

I'm sorry I don't have more to offer regarding the stalling issue. That has got to be frustrating.

[Frank Tabor]

Earlier this week, my ECS light started blinking at me. I looked up the code someone posted on the LML UK forum, and it comes back as an O2 sensor issue. I've seen this type of thing in cars before. More of an annoyance than a serious problem. It doesn't (shouldn't) affect the operation of the vehicle or create any harm, but sheesh, there's less than 500 miles! I'll have the dealer take care of it when I get a chance to take it in.

So then late last night. I was out for a nice, backroads jaunt, and the Stella died on me not once, not twice, but SIX SEPARATE TIMES while I was underway! Six frickin' times I was tooling along, doing anywhere from 35 to 50 mph, running strong when, out of nowhere, the bike just stalls.

The routine became this: coast to the side of the road dead, turn off ignition, wait a few moments, try to restart - but it doesn't catch, wait a few more moments, try to restart, and the bike's running strong again. It was only when I was furthest from home that I finally realized it was going to keep doing this and I'd better head back.

Now here's the punchline… during this time, I also discovered the bike has a short/loose connection/faulty wiring in the taillight. Drive over a bump, taillight goes out. Another bump, taillight comes back on. Not a good thing for driving pitch black country roads, and even worse when you're sitting dead along the side.

I checked out the bulb and it seems snug, but otherwise I'm clueless when it comes to electrics & wiring. So I guess I'm limited to daylight riding until I can get THAT seen to. Grrrrrr!

In perusing the UK forum, it seems the stalling thing is not uncommon, yet almost a year later, there seems to be no definite fix. Having said that, along with sketchy electronic bits, my pride of ownership and confidence in this bike is fading very quickly.

The fact that your O2 sensor light indicates a fault, maybe the gas cap or tank venting is clogged.
A pinched vent tube or clogged gas cap vent would allow a bit of gas to flow then stop then flow again then stop etc.

[caffeine65]

The tailight issue could be a loose wire/connector in the headset (or behind the horncast). I'm guessing the wiring for this is the same as the 4T shifty. If so, it's a yellow wire according to the diagram on page 20:

http://www.modernbuddy.com/pdf/Stella_4 ... manual.pdf

Oh man, THANKS! I'll put that to good use. Besides, I bought a different Vespa horn cast I'm itching to try out.

The fact that your O2 sensor light indicates a fault, maybe the gas cap or tank venting is clogged.
A pinched vent tube or clogged gas cap vent would allow a bit of gas to flow then stop then flow again then stop etc.

I'll look over everything as best I can tonight. I'd originally thought it was a vent issue back when it first started. Maybe I ruled that out too soon? Anyway, the gas cap's not vented in any way I can tell, so maybe I'll drill a hole in it.

[Elder Scoot]

There was an issue with the first bikes regarding one of the tubes associated with the carb that was too long and could kink when someone was riding the bike. Genuine was having the dealer or themselves shorten the tube. Make sure that service was done. Sorry I couldn't be more specific about which tube and what it supposed to do.

[Elder Scoot]

Earlier this week, my ECS light started blinking at me. I looked up the code someone posted on the LML UK forum, and it comes back as an O2 sensor issue. I've seen this type of thing in cars before. More of an annoyance than a serious problem. It doesn't (shouldn't) affect the operation of the vehicle or create any harm, but sheesh, there's less than 500 miles! I'll have the dealer take care of it when I get a chance to take it in.

So then late last night. I was out for a nice, backroads jaunt, and the Stella died on me not once, not twice, but SIX SEPARATE TIMES while I was underway! Six frickin' times I was tooling along, doing anywhere from 35 to 50 mph, running strong when, out of nowhere, the bike just stalls.

The routine became this: coast to the side of the road dead, turn off ignition, wait a few moments, try to restart - but it doesn't catch, wait a few more moments, try to restart, and the bike's running strong again. It was only when I was furthest from home that I finally realized it was going to keep doing this and I'd better head back.

Now here's the punchline… during this time, I also discovered the bike has a short/loose connection/faulty wiring in the taillight. Drive over a bump, taillight goes out. Another bump, taillight comes back on. Not a good thing for driving pitch black country roads, and even worse when you're sitting dead along the side.

I checked out the bulb and it seems snug, but otherwise I'm clueless when it comes to electrics & wiring. So I guess I'm limited to daylight riding until I can get THAT seen to. Grrrrrr!

In perusing the UK forum, it seems the stalling thing is not uncommon, yet almost a year later, there seems to be no definite fix. Having said that, along with sketchy electronic bits, my pride of ownership and confidence in this bike is fading very quickly.

I got a post from LML UK and it is my understanding that they use a different CPU manufactured by Keihin. Their issues had to do with the sensor be set up for a different requirement.

I put away most of tools when engines couldn't be fixed any more with a hammer - but it seems that it might be a heat senor issue - as the bike cools down a bit and then operates - only to heat up again and stop.

[Elder Scoot]

One observation - the bike restarts after a period without opening the gas tank cover. That seems to eliminate an issue with a vacuum in the gas line.

BYW - the gas cap on my 125 is quite tight without any pinhole opening in the cap (unless I have not seen it).

[Frank Tabor]

One observation - the bike restarts after a period without opening the gas tank cover. That seems to eliminate an issue with a vacuum in the gas line.

BYW - the gas cap on my 125 is quite tight without any pinhole opening in the cap (unless I have not seen it).

If the tank is vented, there is no need for a vent hole in the cap so don't make one. And if it runs the same with the gas cap loosened as when it is tight then that is not the issue. I try to eliminate the easy stuff first.

[Neurotic-Hapi-Snak]

The Auto will not have a vented gas tank, just like the 4T doesn't. CARB/EPA requires an evap system. An evap system allows fresh air into the gas tank when there is negative pressure (vacuum), when there is positive pressure (fume build up) the vent to the outside is closed and a carbon canister collects the fumes, releasing them later into the intake air stream. Sometimes the evap system can become flooded with liquid fuel when the tank is over filled and can no longer allow fresh air into the tank, or the valve simply stops working and doesn't allow fresh air into the tank. Simple fix is to allow your tank to vent directly to the outside. No need for a vented gas cap, simply locate your float and sender unit, the large circular item located to the rear of the gas cap. Remove the plastic cover by unscrewing the two slotted brass nuts. You'll now see a large metal circle screwed into the gas tank, in the center is an electrical connector, to one side is a small 90* brass nipple with a rubber hose connected to it. Simply remove the hose clamp from the hose and pull the hose from the nipple. Replace float and sender unit cover. You now have a vented gas tank. If you want, you can remove the rest of the evap fiddly bits or leave them be.

[stASH]

I had a similar issue with the tail light on my shifty 4T early on, and it was just a loose connection on the wire from the light. I found it by pulling the left side cowl and just following the wire back from the tail light. A connector had come loose and all I had to do was plug the two loose ends back in to each other. Super easy fix.

[jimmbomb]

The Auto will not have a vented gas tank, just like the 4T doesn't. CARB/EPA requires an evap system. An evap system allows fresh air into the gas tank when there is negative pressure (vacuum), when there is positive pressure (fume build up) the vent to the outside is closed and a carbon canister collects the fumes, releasing them later into the intake air stream. Sometimes the evap system can become flooded with liquid fuel when the tank is over filled and can no longer allow fresh air into the tank, or the valve simply stops working and doesn't allow fresh air into the tank. Simple fix is to allow your tank to vent directly to the outside. No need for a vented gas cap, simply locate your float and sender unit, the large circular item located to the rear of the gas cap. Remove the plastic cover by unscrewing the two slotted brass nuts. You'll now see a large metal circle screwed into the gas tank, in the center is an electrical connector, to one side is a small 90* brass nipple with a rubber hose connected to it. Simply remove the hose clamp from the hose and pull the hose from the nipple. Replace float and sender unit cover. You now have a vented gas tank. If you want, you can remove the rest of the evap fiddly bits or leave them be.

Awsome info!! Bookmarked for future users.
Thanka alot.

[caffeine65]

There was an issue with the first bikes regarding one of the tubes associated with the carb that was too long and could kink when someone was riding the bike. Genuine was having the dealer or themselves shorten the tube. Make sure that service was done. Sorry I couldn't be more specific about which tube and what it supposed to do.

I had a good look under the hood tonight, and did indeed notice this hose looked suspiciously long:



It also seemed to be fighting with the idle adjustment knob for space beneath the cover plate . So, I ran it around the other side of the knob, shortened it to a more appropriate length, and buttoned everything back up.

Took it out for a spin and experienced NO PROBLEMS! Later, I took it out for a longer ride, and the bike ran great the whole night.

I don't wanna jinx myself by saying "problem solved" but the motorcycle diagnostic tool that resides in my butt says the bike is running better than it ever has.

I also temporarily solved my taillight short with some strategically placed electrical tape. Still getting the ECS code though, but as long as the bike's running fine, it can wait until I see the dealer next.

[Neurotic-Hapi-Snak]

Wow, the Auto gas tank is completely different than the 4T.

That was actually the hose that goes to/comes from your evap valve. No idea if it's the one from the gas tank to the valve, or the one from the valve to the carbon can. I'd assume it's the one from the tank to the valve, because if that one kinked, the vacuum in the tank wouldn't be able to be relieved.

[jimmbomb]

Yes.. from what ive heard... the auto"s main fuel tank sits lower than the carb..
Thats why there is a fuel pump to pump the fuel uphill to a secondary spot above the carb, then gravity takes over and lets the fuel flow to the carb's bowl.

[Elder Scoot]

Yes.. from what ive heard... the auto"s main fuel tank sits lower than the carb..
Thats why there is a fuel pump to pump the fuel uphill to a secondary spot above the carb, then gravity takes over and lets the fuel flow to the carb's bowl.

You are correct. There is a little reservoir container just behind the filler cap that holds the gasoline. A fuel pump pumps gasoline into it and the fuel flows into the throat of the carb. I guess the position of the new motor did not allow the fuel tank to sit above the carb anymore.

[Elder Scoot]

There was an issue with the first bikes regarding one of the tubes associated with the carb that was too long and could kink when someone was riding the bike. Genuine was having the dealer or themselves shorten the tube. Make sure that service was done. Sorry I couldn't be more specific about which tube and what it supposed to do.

I had a good look under the hood tonight, and did indeed notice this hose looked suspiciously long:

<a href="https://www.flickr.com/photos/49986384@N02/14337367079" title="20140627_235325 by Jim Doughty, on Flickr"><img src="https://farm3.staticflickr.com/2927/143 ... 143d_z.jpg" width="579" height="640" alt="20140627_235325"></a>

It also seemed to be fighting with the idle adjustment knob for space beneath the cover plate . So, I ran it around the other side of the knob, shortened it to a more appropriate length, and buttoned everything back up.

Took it out for a spin and experienced NO PROBLEMS! Later, I took it out for a longer ride, and the bike ran great the whole night.

I don't wanna jinx myself by saying "problem solved" but the motorcycle diagnostic tool that resides in my butt says the bike is running better than it ever has.

I also temporarily solved my taillight short with some strategically placed electrical tape. Still getting the ECS code though, but as long as the bike's running fine, it can wait until I see the dealer next.

It's funny how we all attribute magical powers to some mechanical devices - as though thinking a problem is fixed will cause the problem to reoccur. The Stella automatic is a pretty straightforward and simple machine. The ECU makes it stand apart from a lawnmower with 2 wheels and ECU technology has been around since the 1980s. I have great confidence that the little issues along the way will be resolved.

If the issue is resolved let the folks on LML know.

[caffeine65]

Wow, the Auto gas tank is completely different than the 4T.

That was actually the hose that goes to/comes from your evap valve. No idea if it's the one from the gas tank to the valve, or the one from the valve to the carbon can. I'd assume it's the one from the tank to the valve, because if that one kinked, the vacuum in the tank wouldn't be able to be relieved.

It is indeed the hose from tank to valve. Below is a daylight photo for better viewing, although you can't see much with the cover plate back on. Next time I'll take the photo when it's off. You can also see the rectangular reservoir that Elder Scoot mentioned.



Also, there's a small bulkhead in the seat pan (pic below). When the seat is closed, it lightly presses on the top valve hose. It's not crushing it, just a gentle nudge, but I think for good measure, I may trim it a little with a dremel since it probably presses a little harder when I'm on it. The arrow shows the point of contact.

[Elder Scoot]

Wow, the Auto gas tank is completely different than the 4T.

That was actually the hose that goes to/comes from your evap valve. No idea if it's the one from the gas tank to the valve, or the one from the valve to the carbon can. I'd assume it's the one from the tank to the valve, because if that one kinked, the vacuum in the tank wouldn't be able to be relieved.

It is indeed the hose from tank to valve. Below is a daylight photo for better viewing, although you can't see much with the cover plate back on. Next time I'll take the photo when it's off. You can also see the rectangular reservoir that Elder Scoot mentioned.

<a href="https://www.flickr.com/photos/49986384@N02/14526772955" title="20140628_092048 by Jim Doughty, on Flickr"><img src="https://farm3.staticflickr.com/2922/145 ... 1a63_z.jpg" width="640" height="360" alt="20140628_092048"></a>

Also, there's a small bulkhead in the seat pan (pic below). When the seat is closed, it lightly presses on the top valve hose. It's not crushing it, just a gentle nudge, but I think for good measure, I may trim it a little with a dremel since it probably presses a little harder when I'm on it. The arrow shows the point of contact.

<a href="https://www.flickr.com/photos/49986384@N02/14526772925" title="20140628_092342 by Jim Doughty, on Flickr"><img src="https://farm6.staticflickr.com/5037/145 ... 3261_z.jpg" width="360" height="640" alt="20140628_092342"></a>

For some reason I can't open the links to the photos.

[caffeine65]

For some reason I can't open the links to the photos.

Shoot, I think I'm doing images wrong. How about now? I edited the post.

[Elder Scoot]

For some reason I can't open the links to the photos.

Shoot, I think I'm doing images wrong. How about now? I edited the post.

Perfect.

[StellaFelL.A.]

My Stella had it's first stalling episode yesterday. Left work and two blocks away it died. Tried to start it but to no avail. Then I did what some here suggested and took the gas cap off and put it back on. The scoot started up right away. Maybe there is something to this gas cap thing.

[Elder Scoot]

Wow, the Auto gas tank is completely different than the 4T.

That was actually the hose that goes to/comes from your evap valve. No idea if it's the one from the gas tank to the valve, or the one from the valve to the carbon can. I'd assume it's the one from the tank to the valve, because if that one kinked, the vacuum in the tank wouldn't be able to be relieved.

I believe that you are the expert on this question - now that you've seen the set up on the Automatic - how can someone bypass the evap system? Could it be as easy as disconnecting the two hoses and plugging one up and leaving the other one unplugged? This is just a theoretical question as tampering with the system would likely void the warranty.

[Neurotic-Hapi-Snak]

Wow, the Auto gas tank is completely different than the 4T.

That was actually the hose that goes to/comes from your evap valve. No idea if it's the one from the gas tank to the valve, or the one from the valve to the carbon can. I'd assume it's the one from the tank to the valve, because if that one kinked, the vacuum in the tank wouldn't be able to be relieved.

I believe that you are the expert on this question - now that you've seen the set up on the Automatic - how can someone bypass the evap system? Could it be as easy as disconnecting the two hoses and plugging one up and leaving the other one unplugged? This is just a theoretical question as tampering with the system would likely void the warranty.

Just remove the hose that goes from the gas tank to valve. If you want, you can zip tie it (without pinching or kinking it) out of the way. You could also find the nipple on your air intake where the hose from the carbon can goes and put one of those little rubber end caps, like from wire racks and the like, over it to plug it up. But it's probably not necessary since I don't believe air can pass through the carbon can.

Rubber end cap:

[caffeine65]

Quick update: since relieving (what I believed to be) a kink in the hose described above, not only has the bike performed perfectly, but there doesn't seem to be anymore pressure buildup in the fuel tank. Total silence when I remove the gas cap now.

[Elder Scoot]

Quick update: since relieving (what I believed to be) a kink in the hose described above, not only has the bike performed perfectly, but there doesn't seem to be anymore pressure buildup in the fuel tank. Total silence when I remove the gas cap now.

I know the thought might make you nervous (what with the caffeine) - but I think you've fixed the problem. Now just enjoy the bike and let us know if the situation changes.

Also - you might want to let the folks on LML know so that they can duplicate your result.

[caffeine65]

Quick update: since relieving (what I believed to be) a kink in the hose described above, not only has the bike performed perfectly, but there doesn't seem to be anymore pressure buildup in the fuel tank. Total silence when I remove the gas cap now.

I know the thought might make you nervous (what with the caffeine) - but I think you've fixed the problem. Now just enjoy the bike and let us know if the situation changes.

Just posting for posterity is all.

[caffeine65]

Also - you might want to let the folks on LML know so that they can duplicate your result.

Done.

[StellaFelL.A.]

Quick update: since relieving (what I believed to be) a kink in the hose described above, not only has the bike performed perfectly, but there doesn't seem to be anymore pressure buildup in the fuel tank. Total silence when I remove the gas cap now.

So did the ECS light stop coming on. The ECS on mine flashes also. On my way to work yesterday my bike stalled several times. When I was ready to go home the bike wouldn't start at all. I had to get it towed home. I'll be taking it to the shop so can replace the ECU and hopefully that will fix the ECS light and the stalling.

[ericalm]

Quick update: since relieving (what I believed to be) a kink in the hose described above, not only has the bike performed perfectly, but there doesn't seem to be anymore pressure buildup in the fuel tank. Total silence when I remove the gas cap now.

So did the ECS light stop coming on. The ECS on mine flashes also. On my way to work yesterday my bike stalled several times. When I was ready to go home the bike wouldn't start at all. I had to get it towed home. I'll be taking it to the shop so can replace the ECU and hopefully that will fix the ECS light and the stalling.

Who is your dealer in the SGV?

[ericalm]

My Stella had it's first stalling episode yesterday. Left work and two blocks away it died. Tried to start it but to no avail. Then I did what some here suggested and took the gas cap off and put it back on. The scoot started up right away. Maybe there is something to this gas cap thing.

That'll work sometimes but you can also get gas in the hoses, which will choke off air and cause a stall.

The evap system issues affect many scooters from many companies. The first tech thread on Modern Vespa is how to disable the damn thing. Unfortunately, OEMs have little recourse. The state of CA mandates not just the system but aspects of its design, which don't work well with the placement of a lot of gas tanks. So, while it's illegal to disable it in CA, there are many ways for those in other states to do this. A steel bearing in the hose coming from the tank works well. It's the kind of thing that no one would ever notice.

[caffeine65]

So did the ECS light stop coming on. The ECS on mine flashes also. On my way to work yesterday my bike stalled several times. When I was ready to go home the bike wouldn't start at all. I had to get it towed home. I'll be taking it to the shop so can replace the ECU and hopefully that will fix the ECS light and the stalling.

The ECS light isn't just coming on, but rather it's blinking. I'm inclined to believe it's a separate issue though. The four-blink error code, according to the Star Auto UK forums, points to the O2 sensor.

The bike is running fantastic however, so screw it, I'm riding until I can have the dealer check it out. If I assume it works just like the O2 sensor in any other car or motorcycle, it should be fine.

EDIT: Also, something I noticed a few weeks back is, the spill-over light inside the dash is so much that at night the ECS light might appear to be on when it isn't.

[StellaFelL.A.]

Quick update: since relieving (what I believed to be) a kink in the hose described above, not only has the bike performed perfectly, but there doesn't seem to be anymore pressure buildup in the fuel tank. Total silence when I remove the gas cap now.

So did the ECS light stop coming on. The ECS on mine flashes also. On my way to work yesterday my bike stalled several times. When I was ready to go home the bike wouldn't start at all. I had to get it towed home. I'll be taking it to the shop so can replace the ECU and hopefully that will fix the ECS light and the stalling.

Who is your dealer in the SGV?

Actually there is no Genuine dealer in my area. I bought it from the dealer in Marina Del Rey.

[caffeine65]

The evap system issues affect many scooters from many companies. The first tech thread on Modern Vespa is how to disable the damn thing. … A steel bearing in the hose coming from the tank works well. It's the kind of thing that no one would ever notice.

Eric, I'm new to scootering and know nothing about evap systems, so correct me if I'm wrong, but this sounds counter to what I experienced. Only after I unblocked this hose does the bike run the way it should. It also seems to ventilate the fuel tank; I've yet to get any PSSST! when removing the gas cap like before.

BUT… like I said, zero knowledge of these systems, so it's likely I'm missing something here.

Also, out of curiosity, assuming the bike's running fine, is there any benefit to disabling the evap system? Like a performance gain or something? Or is it just for simplification?

[StellaFelL.A.]

So did the ECS light stop coming on. The ECS on mine flashes also. On my way to work yesterday my bike stalled several times. When I was ready to go home the bike wouldn't start at all. I had to get it towed home. I'll be taking it to the shop so can replace the ECU and hopefully that will fix the ECS light and the stalling.

The ECS light isn't just coming on, but rather it's blinking. I'm inclined to believe it's a separate issue though. The four-blink error code, according to the Star Auto UK forums, points to the O2 sensor.

The bike is running fantastic however, so screw it, I'm riding until I can have the dealer check it out. If I assume it works just like the O2 sensor in any other car or motorcycle, it should be fine.

EDIT: Also, something I noticed a few weeks back is, the spill-over light inside the dash is so much that at night the ECS light might appear to be on when it isn't.

So a bad ECU wouldn't necessarily cause stalling? Maybe I'll go ahead and check that hose and play around with it.

[caffeine65]

So a bad ECU wouldn't necessarily cause stalling? Maybe I'll go ahead and check that hose and play around with it.

I don't know enough about the ECU to say what it would or wouldn't do, but let me put it this way...

After ECU replacement:
- No more sluggish behavior
- No more engine racing
- No more flat spot in the throttle
- Easier starting

After shortening the hose from tank to evap valve:
- No more stalling/dying while underway
- No more pressure buildup in fuel tank

Still have:
- ECS error code (which I believe is O2 sensor)

So by all appearances, I've had several different issues going on at once. But I could be wrong! I'm only a shade tree mechanic at best.

[StellaFelL.A.]

So a bad ECU wouldn't necessarily cause stalling? Maybe I'll go ahead and check that hose and play around with it.

I don't know enough about the ECU to say what it would or wouldn't do, but let me put it this way...

After ECU replacement:
- No more sluggish behavior
- No more engine racing
- No more flat spot in the throttle
- Easier starting

After shortening the hose from tank to evap valve:
- No more stalling/dying while underway
- No more pressure buildup in fuel tank

Still have:
- ECS error code (which I believe is O2 sensor)

So by all appearances, I've had several different issues going on at once. But I could be wrong! I'm only a shade tree mechanic at best.

Thanks for the breakdown. I"ll give the hose shortening a go and see what results I get.

[Neurotic-Hapi-Snak]

Also, out of curiosity, assuming the bike's running fine, is there any benefit to disabling the evap system? Like a performance gain or something? Or is it just for simplification?

Simplification/removal of source of potential problem.

Theoretically, you may get less gas mileage, since some of your gas is escaping to the air rather than being fed back into the intake airstream. Also evap on a carbed engine could theoretically cause issues with the fuel/air ratio, since it's feeding unmetered fuel vapor into the intake. On most modern cars, the ECU also controls the evap system and feeds the vapors into the intake at high throttle, when they'll have the least impact. It also takes it into account and adjusts the amount of fuel injected into the cylinder (closed loop operation).

I say theoretically, because I believe both of these have very little real world impact, probably much less than the weather does. And the amount of fuel vapor captured is so small that I believe it has very little impact on either mpg or fuel/air ratio.

[Elder Scoot]

Wow, the Auto gas tank is completely different than the 4T.

That was actually the hose that goes to/comes from your evap valve. No idea if it's the one from the gas tank to the valve, or the one from the valve to the carbon can. I'd assume it's the one from the tank to the valve, because if that one kinked, the vacuum in the tank wouldn't be able to be relieved.

I believe that you are the expert on this question - now that you've seen the set up on the Automatic - how can someone bypass the evap system? Could it be as easy as disconnecting the two hoses and plugging one up and leaving the other one unplugged? This is just a theoretical question as tampering with the system would likely void the warranty.

Just remove the hose that goes from the gas tank to valve. If you want, you can zip tie it (without pinching or kinking it) out of the way. You could also find the nipple on your air intake where the hose from the carbon can goes and put one of those little rubber end caps, like from wire racks and the like, over it to plug it up. But it's probably not necessary since I don't believe air can pass through the carbon can.

Rubber end cap:

Would it be as easy as simply removing the bottom hose (tank to valve) to vent the tank -- and then simply plugging the top hose? Both hoses could be left in place making the reconnection process very simply.

[Neurotic-Hapi-Snak]

That would work.

[StellaFelL.A.]

It is indeed the hose from tank to valve.

So is the other hose supposed to be connected somewhere. I found it dangling just by itself. I pulled it out so I could take a picture of it. The end of the hose has an indentation like if it supposed to be clamped somewhere. I'm thinking it goes to that tube I have circled in red. It's under the left cowl.

[caffeine65]

So is the other hose supposed to be connected somewhere. I found it dangling just by itself. I pulled it out so I could take a picture of it. The end of the hose has an indentation like if it supposed to be clamped somewhere. I'm thinking it goes to that tube I have circled in red. It's under the left cowl.

I went and looked at mine, and yes it is connected there. Wow that's strange. I wonder why yours is off! Mine is even clamped on.

[caffeine65]

Also, out of curiosity, assuming the bike's running fine, is there any benefit to disabling the evap system? Like a performance gain or something? Or is it just for simplification?

Simplification/removal of source of potential problem.

Theoretically, you may get less gas mileage, since some of your gas is escaping to the air rather than being fed back into the intake airstream. Also evap on a carbed engine could theoretically cause issues with the fuel/air ratio, since it's feeding unmetered fuel vapor into the intake. On most modern cars, the ECU also controls the evap system and feeds the vapors into the intake at high throttle, when they'll have the least impact. It also takes it into account and adjusts the amount of fuel injected into the cylinder (closed loop operation).

I say theoretically, because I believe both of these have very little real world impact, probably much less than the weather does. And the amount of fuel vapor captured is so small that I believe it has very little impact on either mpg or fuel/air ratio.

Thanks! Yeah that sounds uneccessarily complicated, lol. I think I'll leave mine alone for now though, since the bike's running great. But good info to have someday when I feel like tinkering.

[StellaFelL.A.]

So is the other hose supposed to be connected somewhere. I found it dangling just by itself. I pulled it out so I could take a picture of it. The end of the hose has an indentation like if it supposed to be clamped somewhere. I'm thinking it goes to that tube I have circled in red. It's under the left cowl.

I went and looked at mine, and yes it is connected there. Wow that's strange. I wonder why yours is off! Mine is even clamped on.

Ok thanks. I'll go ahead and connect it then. I've shortened the other hose and now hopefully there will be no more stalling!

[Dooglas]

Also, out of curiosity, assuming the bike's running fine, is there any benefit to disabling the evap system? Like a performance gain or something? Or is it just for simplification?

Simplification/removal of source of potential problem.

I have owned 6 scooters with evap systems and never any kind of tank venting problem. East to diagnose in any case. Makes you wonder why so many people recommend disconnecting the evap system as the solution to almost any imaginable problem. Seems to me the right answer is to solve the problem if you have it. Otherwise why not focus on a real solution.