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@sc68ter avatar
UTC

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2018 GTS 300 Super Sport (Grey)
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@sc68ter avatar
2018 GTS 300 Super Sport (Grey)
Joined: UTC
Posts: 46
Location: Surrey, England
UTC quote
Sorry folks, I know that these pop up a lot, but having read them all I cannot find anything quite like my issue.

So, the basics:

2018 GTS 300 Super Sport with 1,100 miles

Since new I have had a very occasional non-start but it was so sporadic that it proved impossible to locate. It was also so infrequent that I didn't bother.

Of late it has taken to happening more often, especially when nice and hot (weather and/or scooter).

I started noticing it initially after a run when I put it on the side-stand to open the garage door.

I would push the side stand down to kill the motor but on re-start it was as dead as a dodo. Full electrics but nothing from the starter button.

I have trawled this site and checked the codes on the flashing red light - all good. I get constant brake lights, so ruling out the brake light switch front and rear.

I was beginning to think it could well be a duff side stand switch until I used the centre stand a couple of time and the same thing happened.

As it isn't heavy I typically just wheel it into the garage, after which time it then comes back to life and starts on the first press of the starter button.

Last weekend was a lovely warm weekend here in Blighty with it pushing 30 degrees so I rode to see a friend. I parked up on her drive and when i came to move it about 15 mins later it wouldn't start. All lights were active, brakes flashed but nothing from the starter button.

I pushed it around to the back gate (was leaving it and going out in the car) and it immediately fired up.

Came to leave a couple of hours later and rode about five mins and then pulled over to make a phone call. When I went to start the motor again it made a sound as if the starter spun over for about half a second and then nothing.

After about 10 mins of sitting and getting progressively hotter, I took off my helmet and then wondered whether a push might work - and it did! Fired on the first press of the start.

So I am beginning to wonder whether me rolling the scooter around a bit allows something that isn't engaging, to engage.

Could the starter motor (does it even have a start motor?) have a flat spot on it, that i need to roll over which then allows the motor to start?

The battery is brand new because I forgot to switch my trickle charger on over winter and it died, I always get a brake light and no matter how much I operate the side stand it makes to odds to the restart, so I think I am on to something, I just don't know what!

Any help/thoughts/opinions very welcome, as I would like to get this sorted before it fails fully and strands me somewhere.

Thanks in advance,

SC68TER
@der_blechfahrer avatar
UTC

Molto Verboso
ET3 & PX150 & GTS 300 Super Sport MY23 & Yamaha Neo's electric
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Molto Verboso
@der_blechfahrer avatar
ET3 & PX150 & GTS 300 Super Sport MY23 & Yamaha Neo's electric
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UTC quote
It does have a starter.
@kaptainkid avatar
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2006 Vespa GT 200L
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Location: Los Angeles
 
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@kaptainkid avatar
2006 Vespa GT 200L
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Posts: 47
Location: Los Angeles
UTC quote
Could have been bad or loose connection to battery. It might have resolved it self with new battery. Also could be loose ground wire or bad main fuse(fuse going bad). Check all fuses and by pulling then out and putting back helps with proper fuse connection too. Final check would be check all connection and wires to see if they are loose.
OP
@sc68ter avatar
UTC

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2018 GTS 300 Super Sport (Grey)
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@sc68ter avatar
2018 GTS 300 Super Sport (Grey)
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Location: Surrey, England
UTC quote
Thank you.

The problem has persisted with the fitting of the new battery but appreciate the thought.

Will work through the fuses, as that is something that I hadn't considered.

Perhaps I allowed myself to get distracted by rolling the bike, thinking that this was somehow allowing it to start - a job for the weekend me thinks!

Thanks again.
@lottolearn avatar
UTC

Hooked
2019 Liberty 150
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Hooked
@lottolearn avatar
2019 Liberty 150
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Location: NEPA
UTC quote
This should be fairly easy you just have to be ready. You need the wiring diagram https://manuals.wotmeworry.org.uk/Vespa/GTS300%20Super/GTS300%20Super%20Wiring%20Diagram.pdf a meter and to locate the starter relay. When it doesn't start you can test the starter circuit at the relay so you have to be aware of its location and be able to access. One other thing you might try is to bypass the side stand switch, unplug and jump out the pins (harness side) and see if that corrects. I would also remove the side stand because it will start with it down and if you forget to put it up it will hurt. Since you're at the switch you can test it there with an ohm meter for proper operation. Put on center stand unplug side stand switch from harness, install ohm meter, cycle stand up and down several times and see if you end up with high resistance or OC when stand is up. If this makes zero sense find somebody near who can help you.
Or this can be a common issue and someone will tell you the exact cause and how to correct.
Best of luck.
UTC

Molto Verboso
Vespa GTS 300
Joined: UTC
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Location: Germany
 
Molto Verboso
Vespa GTS 300
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Location: Germany
UTC quote
If I understand correctly, the problem is that it does not start at times (when warm)?

Then you can rule out the fuses as the cause (either OK or defective, but not temporary).

Kill switch switched multiple times?
Side stand switch is also possible cause (even if the error occurred when using the main stand).

Please describe exactly what happens / does not happen when you want to start (noises, etc.).

Do you hear the fuel pump whirring when you turn the key to "on"?

Have you tried using the master key (instead of the blue key) when the problem is acute? How does the immobilizer indicator light light up/flash when you try to start the car without success?
@lottolearn avatar
UTC

Hooked
2019 Liberty 150
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Location: NEPA
 
Hooked
@lottolearn avatar
2019 Liberty 150
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UTC quote
From what I can tell the stater relay is a simple version.
You have 12 VDC direct from the battery to the high amp switch on the relay, the other high amp relay lead goes direct to the starter. On the coil side of the relay the ground is provided by the ECU. the power side of the relay coil comes from a fuse, to the brake light switches, to the start switch, to the relay +side of the coil. You can perform a lot of tests at the relay and work from there. If you remove everything from the wiring diagram and just focus on the start circuit it is a pretty simple system. Your biggest challenge is it's intermittent.

If you are not getting the ground signal to the starter relay coil then it could be the side stand switch, kill switch, etc.
⬆️    About 2 months elapsed    ⬇️
OP
@sc68ter avatar
UTC

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2018 GTS 300 Super Sport (Grey)
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@sc68ter avatar
2018 GTS 300 Super Sport (Grey)
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Location: Surrey, England
UTC quote
Hi all and thanks for the various thoughts and suggestions; greatly appreciated!

I am no electrician, so most of what has been suggested is so far over my head that I wouldn't know where to start, but I am still of the mind that this isn't an electrical circuit but "something else" - something mechanical.

I went out for a run on Sunday and it was a lovely, lovely run.

When I did finally stop I had problems on starting again.

This time, when i hit the starter button the starter motor started turning over briefly then stopped after about a second and then nothing more.

I rolled the scooter forwards a metre and tried again, and it sprang back into life, cranked and fired.

I cannot help think that this feels like a flat-spot on the starter motor - but to be honest I don't even know what this means mechanically.

Is it possible that the starter motor (or something else involved with the starting of the scooter) sticks, and by me rolling forwards a bit causes it to either release or move over the flat-spot and therefore start?

Would value any opinions/thoughts on this as I cannot see how something electrical can be nudged into working by physically moving the scooter.

Many thanks all
@blackguard avatar
UTC

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GTS 300
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Location: Western Massachusetts
 
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@blackguard avatar
GTS 300
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UTC quote
Do you have an apple AirTag on your key ring? It is possible that it is interfering with the antenna in the immobilizer. Could also be a wonky antenna connection.
OP
@sc68ter avatar
UTC

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2018 GTS 300 Super Sport (Grey)
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@sc68ter avatar
2018 GTS 300 Super Sport (Grey)
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Location: Surrey, England
UTC quote
Hi Blackguard and thanks for the response.

Only things on my key ring are two Oxford lock keys and the ignition key.

I read somewhere about the light sequence of the immobiliser which would show that it was deactivated (or not) and think mine works fine.

I also get a brake light which I assume I wouldn't if the immobiliser was still on?

Oh well, on with the search!

😊
@steelbytes avatar
UTC

Veni, Vidi, Posti
2019 GTS300 Supertech E3 59,000km
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@steelbytes avatar
2019 GTS300 Supertech E3 59,000km
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Location: Batmania aka Melbourne, Australia
UTC quote
SC68TER wrote:
Hi Blackguard and thanks for the response.

Only things on my key ring are two Oxford lock keys and the ignition key.

I read somewhere about the light sequence of the immobiliser which would show that it was deactivated (or not) and think mine works fine.

I also get a brake light which I assume I wouldn't if the immobiliser was still on?

Oh well, on with the search!

😊
Brake light working or non working has no bearing on the immobiliser. It does though affect if the ecu will allow a start.

The immobiliser light should go off and stay off when turning on the ignition. If it doesn't then it's the immobiliser at fault and the ecu will refuse to attempt a start.
@blackguard avatar
UTC

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GTS 300
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@blackguard avatar
GTS 300
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UTC quote
What SteelBytes said. My 2018 GTS did exactly the same thing. Stranded me on several occasions and I got so frustrated that I finally traded it in on a 2023. Seacoast gave me a great deal and I couldn't pass it up. / I would suggest replacing the immobilizer antenna. This should be a Vespa warranty issue as it is a common problem. I hope you get it resolved. Jon
@jimc avatar
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The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
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@jimc avatar
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
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UTC quote
Blackguard wrote:
I would suggest replacing the immobilizer antenna. This should be a Vespa warranty issue as it is a common problem. I hope you get it resolved. Jon
Why proceed with this expensive part replacement? No evidence has been produced to suggest that the immobiliser system is at fault. If the LED goes out after switch-on, the immobiliser is happy, 'nuff said.

This sounds like a bad or dodgy connection, probably in the kill-switch if that's been used often to turn the scooter off.
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@sc68ter avatar
UTC

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2018 GTS 300 Super Sport (Grey)
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UTC quote
Update:

Sunday I went to start my scooter and for the first time in memory (and from cold - parked up all night) the starter made a half attempt to start and then absolutely nothing.

Could hear the fuel pump, immobiliser light was out, all dash lights were correct and I had a brake light on both levers but the starter button did nothing.

I left it a little while (minutes) but still nothing so paddled around a bit, bouncing on the seat.

Couple of paddles and the starter sprang back into life and all was well once more.

I still can't get over the mind that something is sticking and me bumping it is freeing it off.

Anyone got any thoughts - no matter how random - just want to get to the bottom of it as it made me half an hour late yesterday, and next time might be much worse!

Thanks all
@jimc avatar
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The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
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@jimc avatar
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
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UTC quote
Have you checked all the high current connections to the starter are good, non-corroded and tight?

Battery +ve
Starter relay in
Starter relay out
Starter +ve connection.
Starter -ve connection
Battery -ve to frame
Frame to engine.
@dougw avatar
UTC

Hooked
1974 Rally200, 2007 GTS250ie
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Location: Lawrence, KS
 
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@dougw avatar
1974 Rally200, 2007 GTS250ie
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UTC quote
I have had this problem. I was advised not to use the red kill switch and to only swith on/off using the key. I think I'd known that, but at some point got in the habit of using the kill switch every time to shut off. I put some tape over the kill switch temporarily to remind myself until I stop using it reflexivly. Bike has been starting reliably since (it's only been a week or two).
UTC

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GTS Supertech 300
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Location: Southwest Florida USA
 
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GTS Supertech 300
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Location: Southwest Florida USA
UTC quote
The US versions have a kick stand switch that prevents its starting if the kick stand is down. If the switch is bad it would not start If yours has one you want check that. If the contacts in the switch are bad or there is a lose connection that could cause a no start. I hate that feature on mt GTS Supertech 300. For that reason I always use my center stand.
@cdwise avatar
UTC

Veni, Vidi, Posti
GTS 300, Buddy 125
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@cdwise avatar
GTS 300, Buddy 125
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Posts: 8870
Location: Knoxville, TN
UTC quote
Is it just me or does the "bouncing up and down" making a difference in when it starts make anyone else want to check the spark plug wire and cap?

Personally I'd take it in for a code reading.
@jimc avatar
UTC

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The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
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@jimc avatar
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
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UTC quote
cdwise wrote:
Is it just me or does the "bouncing up and down" making a difference in when it starts make anyone else want to check the spark plug wire and cap?

Personally I'd take it in for a code reading.
From the first post 'dead as a dodo' eliminates the spark as a problem - it's not even trying to start, i.e. not turning over at all.
@crackedegg avatar
UTC

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2018 Vespa GTS300
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@crackedegg avatar
2018 Vespa GTS300
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UTC quote
Opening the throttle stops the starter from turning. When you are moving the bike after a no-start maybe the throttle is being closed so then it will start.
⬆️    About 1 month elapsed    ⬇️
OP
@sc68ter avatar
UTC

Member
2018 GTS 300 Super Sport (Grey)
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Posts: 46
Location: Surrey, England
 
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@sc68ter avatar
2018 GTS 300 Super Sport (Grey)
Joined: UTC
Posts: 46
Location: Surrey, England
UTC quote
CrackedEgg wrote:
Opening the throttle stops the starter from turning. When you are moving the bike after a no-start maybe the throttle is being closed so then it will start.
OMG!!!

I have held off posting on this so as to be totally sure that I was right but CrackedEgg was right on the money - thank you so much!!!

Since pointing out the throttle being connected to the starter I have made a conscious effort to keep my hand off it.

Not one single non-start event since then (other than the one occasion where I forgot to pull on the brake lever and got myself into a proper tiz!).

So as a close to this post I wanted to thank everyone who contributed and especially to CrackedEgg for the simple wisdom of keeping it simple/stupid and solving my five year dilemma!

Thank you 🙏
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