2012 Stella 4T - even the mechanic can't figure this one out

adamwisneski · Post by **adamwisneski** » Fri Aug 22, 2014 6:21 pm

Hey all,

I recently bought a used 2012 Stella from a shop. Since i bought it, it's always had seemingly random problems at times staying running. For example, It will run perfect for 20 minutes and then will just die at a stoplight. And after, it might take me 10 minutes to get it started again.

It's unreliable. Sometimes it runs with hiccups in idle or acceleration, and I have to keep the throttle up so that it doesn't die on me. And progressively the problem worsened to now, where the scoot won't stay running for more than 60 seconds.

The mechanic has checked and cleaned the carbs twice now, with no change in performance. I've checked the spark plug against the frame, getting spark. I checked the fuel filter and line, which is not clogged or crimped. I've adjusted the idle, and made sure the float in the carb wasn't sticking. It doesn't matter what temp it is outside either. results are the same.

And recently, the mechanic bought me a brand new carb and I put it on there, and it hasn't changed a thing. Same issue, won;t run for more than 60 seconds.

I really don't know what to try next. i thought the new carb might fix it. Anybody out there have any ideas?

Really appreciate it.

Stilts · Post by **Stilts** » Fri Aug 22, 2014 6:28 pm

I know you've checked the fuel line, but what about the petcock/gasket inside the fuel tank itself?

adamwisneski · Post by **adamwisneski** » Fri Aug 22, 2014 7:24 pm

Sounds good. I can try that out. IN the service manual it says to use a special tool RS-00231. Is that necessary in your opinion?

When petcock turned to "on" fuel does in fact drip out of the fuel line. But should I check anyway?

Thanks again.

jimmbomb · Post by **jimmbomb** » Fri Aug 22, 2014 9:19 pm

adamwisneski wrote:Sounds good. I can try that out. IN the service manual it says to use a special tool RS-00231. Is that necessary in your opinion?

When petcock turned to "on" fuel does in fact drip out of the fuel line. But should I check anyway?

Thanks again.

Unhook the fuel line from the carb and let the fuel flow into a can or bottle or something.
If the flow is good (I mean alot). . Then cool. .
Also crack the gas cap open while youre doing this..
If the flow is just dribbling. .
Thats fuel starvation! !
Good luck

djp4059 · Post by **djp4059** » Fri Aug 22, 2014 11:48 pm

Next time it doesn't want to start or dies out on you, open the drain screw on the carb's bowl and see if any gas comes out. The bowl doesn't hold a whole lot of gas so you could catch it coming out of the drain hose with something small.

Post by **ericalm** » Tue Aug 26, 2014 4:51 am

Have you disconnected or disabled the evap system yet?

Tipper · Post by **Tipper** » Tue Aug 26, 2014 1:15 pm

It may not be a fuel issue,the LML coil is known for breaking down when hot or at random intervals and the symptoms feel exactly like fuel starvation.

I would ask him to swap out the coil,its a very common fault.

Dooglas · Post by **Dooglas** » Tue Aug 26, 2014 3:30 pm

Tipper wrote:It may not be a fuel issue, the LML coil is known for breaking down when hot or at random intervals and the symptoms feel exactly like fuel starvation.

I'm with you. I don't think this is a fuel problem, especially after everything which has been tried with no change. I think this is an intermittent electrical problem.

Frank Tabor · Post by **Frank Tabor** » Fri Aug 29, 2014 2:27 am

Dooglas wrote:
Tipper wrote:It may not be a fuel issue, the LML coil is known for breaking down when hot or at random intervals and the symptoms feel exactly like fuel starvation.
I'm with you. I don't think this is a fuel problem, especially after everything which has been tried with no change. I think this is an intermittent electrical problem.

My 2009 2T acted like it had fuel problem too. I replaced the OEM ignition coil and CDI unit with a Ducati combined CDI/coil unit and it has never run better for past 8K miles.
A 4T Stella shifter completed the 3,800 mile AK to NOLA race this past Scooter Cannonball without one problem.
FWIW.

spacewolf42 · Post by **spacewolf42** » Fri Apr 10, 2015 3:59 am

I am having similar issues with my 2012 4t stella. I am thinking about swapping the coil out. I already had the carb cleaned twice and took it to Vespa Dallas and they said they didn't have any issues when they Took it for a long ride. Any suggestions for a suitable replacement coil?

Yalzin · Post by **Yalzin** » Fri Apr 10, 2015 3:35 pm

ericalm wrote:Have you disconnected or disabled the evap system yet?

I would consider trying this. I had issues similar to what the OP stated...after the bike warmed up, it would randomly bog down and die. Turned out fuel was getting into the evap system/canister. I plugged it and got a 2T vented cap, and have not had an issue since.

jamisfoes · Post by **jamisfoes** » Fri Apr 10, 2015 3:37 pm

At first I thougt it was a evap issue but it turns out that it's a spark plug issue. Try to pull up on the rubber boot of the spark plug cable and if it comes right off, you have the same problem as I do. Mine was very loose and lose contact which caused the scooter to die. I just tape it so it won't come loose, after I did this the problem is solved.

I have a 4T 2010 Stella

az_slynch · Post by **az_slynch** » Fri Apr 10, 2015 4:21 pm

John K. Had an issue like this, which came to a head when the scoot died on a mountain ride and wouldn't restart. No spark. Check the plug boot and wire. Ultimately, I tested the charging coil for the CDI, located on the stator. It had shorted internally. Replaced the stator plate and it's been fine ever since.

Tip: if you don't have a 4T stator, a '03-'05 Stella 2T stator can be fitted if removed from it's backing plate. You'll need to swap the connectors and bring the pulser (trigger) coil along as well.

79_Limited · Post by **79_Limited** » Sun Apr 12, 2015 10:58 pm

Yalzin wrote:
ericalm wrote:Have you disconnected or disabled the evap system yet?
I would consider trying this. I had issues similar to what the OP stated...after the bike warmed up, it would randomly bog down and die. Turned out fuel was getting into the evap system/canister. I plugged it and got a 2T vented cap, and have not had an issue since.

I had the same issue with my 4T brand new. Would just die for no reason. As others suggested I plugged the evap system and it ran fine.

jmer1234 · Post by **jmer1234** » Mon Jun 08, 2015 8:13 pm

Frank Tabor wrote:
Dooglas wrote:
Tipper wrote:It may not be a fuel issue, the LML coil is known for breaking down when hot or at random intervals and the symptoms feel exactly like fuel starvation.
I'm with you. I don't think this is a fuel problem, especially after everything which has been tried with no change. I think this is an intermittent electrical problem.
My 2009 2T acted like it had fuel problem too. I replaced the OEM ignition coil and CDI unit with a Ducati combined CDI/coil unit and it has never run better for past 8K miles.
A 4T Stella shifter completed the 3,800 mile AK to NOLA race this past Scooter Cannonball without one problem.
FWIW.

Frank,

Are you saying the 4T also had a Ducati CDI/coil? I have been chasing the stalling once warmed up problem for a while myself, and have exhausted the fuel avenues. I am starting to look at the ignition system.

Does anybody else have experience with aftermarket CDI or coil on the 4T Stella?

jmer1234 · Post by **jmer1234** » Mon Jun 08, 2015 8:14 pm

Frank Tabor wrote:
Dooglas wrote:
Tipper wrote:It may not be a fuel issue, the LML coil is known for breaking down when hot or at random intervals and the symptoms feel exactly like fuel starvation.
I'm with you. I don't think this is a fuel problem, especially after everything which has been tried with no change. I think this is an intermittent electrical problem.
My 2009 2T acted like it had fuel problem too. I replaced the OEM ignition coil and CDI unit with a Ducati combined CDI/coil unit and it has never run better for past 8K miles.
A 4T Stella shifter completed the 3,800 mile AK to NOLA race this past Scooter Cannonball without one problem.
FWIW.

Frank,

Are you saying the 4T also had a Ducati CDI/coil? I have been chasing the stalling once warmed up problem for a while myself, and have exhausted the fuel avenues. I am starting to look at the ignition system.

Does anybody else have experience with aftermarket CDI or coil on the 4T Stella?

JohnKiniston · Post by **JohnKiniston** » Mon Jun 08, 2015 9:37 pm

The 4T does not use the ducati setup.

Interestingly enough the CDI off a Honda Elite 80 works.

jmer1234 · Post by **jmer1234** » Tue Jun 09, 2015 1:11 am

Does anybody know if the direct ignition from NCY will fit under the cowl?

http://www.monsterscooterparts.com/dire ... s-ncy.html

ArgonV · Post by **ArgonV** » Wed Jun 10, 2015 3:22 pm

Ok, so my Stella started doing something strange the past few months. If I hadn't ridden her day after day and let her sit for a few days or more this would happen:

-Starts up with the choke pulled after a few kicks. Warms up fine within the first few minutes.

-Take a mile or so drive.

-Engine starts sputtering and eventually dies.

-Engine would then start to idle rough and take more kicks to get going.

-After 20-30 minutes of this, the scooter would run fine, and continue to do so if ridden day after day.

This had my mechanics stumped! And they could replicate the issue... Well someone decided to run a vacuum test on the gas tank and low and behold a one way valve was getting stuck in that little plastic cylinder above the gas tank where the evap emissions lines go to. They replaced this part under warranty and the scooter has been running fine ever since.

jimmbomb · Post by **jimmbomb** » Wed Jun 10, 2015 3:46 pm

ArgonV wrote:Ok, so my Stella started doing something strange the past few months. If I hadn't ridden her day after day and let her sit for a few days or more this would happen:

-Starts up with the choke pulled after a few kicks. Warms up fine within the first few minutes.

-Take a mile or so drive.

-Engine starts sputtering and eventually dies.

-Engine would then start to idle rough and take more kicks to get going.

-After 20-30 minutes of this, the scooter would run fine, and continue to do so if ridden day after day.

This had my mechanics stumped! And they could replicate the issue... Well someone decided to run a vacuum test on the gas tank and low and behold a one way valve was getting stuck in that little plastic cylinder above the gas tank where the evap emissions lines go to. They replaced this part under warranty and the scooter has been running fine ever since.

Can you get us the part number? Thanks

ArgonV · Post by **ArgonV** » Wed Jun 10, 2015 4:17 pm

It's the fuel over floating cut off valve. I'll see if I can find the part #...

spacewolf42 · Post by **spacewolf42** » Wed Jun 10, 2015 10:28 pm

Just picked up my stella from the shop and turns out I had a bad stator. They had another 2012 4t with the same problem a week before I brought mine in. Just something to keep in mind because I had similar issues with sputtering and loss of power.

ArgonV · Post by **ArgonV** » Sun Jun 21, 2015 4:33 pm

Well, the problem has returned for me... But I think this time it's my fault! See, I left for 5 days but I left the fuel petcock in the On position and I didn't burn out all the fuel in the carb. Could that have caused my stuttering and stalling at higher gears the past 2 days? I think I've burnt it all out of the jets now and it's starting to regain power in 3rd and 4th on long rides with near WOT.

ArgonV · Post by **ArgonV** » Tue Jun 30, 2015 2:29 pm

Ok I think it's sorted now...

After cleaning the jets, what I did was unplug the hose going from the top of the fuel tank to the little fuel over floating cut off valve so the tank can vent and not create a tank vacuum issue when sitting for extended periods.

I also noticed that the wire connections going into the engine magneto were loose. How you may ask? When I was diagnosing the problem I had to move some wires out of the way under the engine cowl when the engine was running. It was idling fine until I moved the wires, then the engine started to die! The connections were under that little plastic box with the single screw through the center of it on the top rear of the engine. I reseated them and tested - ran great.

I had to leave the state for a wedding for 5 days... So on my last ride I closed the fuel petcock and ran the gas out of the carb bowl. When I got back to town, I opened the fuel valve, pulled the choke and she fired right up! Let her warm for a couple of minutes and went for a long drive. No problems what so ever.