Modern Vespa

Hi everyone, problem with my 2010 GTS. She starts when starter switch depressed but shuts of when switch is released.

Eventually stays on….. for now……

Welcome to MV, allantzke!

Sounds like an odd issue. Someone will be along shortly to help you out. While you wait, post some pics of your GTS. That's a surefire way to draw folks in and get them talking.

Can you describe the issue a little bit more precise?
So you switch on the ignition key, hold one of the brake levers, you press the starter button, the starter motor runs and what happens then? Does the engine fire up or not?

Hi a Peter CC,

Yes engine fires, can hear starter motor turning over. Release starter button and engine stops.

Seems to be switch related to me. Not knowing how the switch works I'm unsure how to diagnose.

Allan

Does the starter motor make a louder noise than usual, or seem to be turning over slower than previously? I'm wondering if the sprag clutch has seized up in some way. If so, this'd be the second one in a few days, one of the MP3 owners is suffering this. I had it on my Fuoco back in the day.

Yes I did notice a strange noise. I couldn't tell you where from but it was toward front of engine I think. Sounds like a possibility.

See this post:
https://modernvespa.com/forum/post2515211#2515211

That is not what I meant with firing up.
The starter motor works and the engine is crancking. But does the engine fire, takes over, the point when you normally release the starter button? Does it do that? And then when you release the button the engine stops?
From what you have described so far it looks like a normal starting problem. If you would be running out of gas (as an example) you would experience the same behavior. The engine does not take over.

I see what you mean. Indeed could also be but so far from the description of allantzke it is not yet clear to me what the phenomenon really is.

Hi folks, thank you for you time on this. Yes the engine does take over but then stops. Plenty of fuel.

Plan on riding her today so will see if it happens again.

So it is not always happening? Sometimes at start up all is normal and sometimes the engine stops when you release the starter button?

If so, that sounds more and more like the sprag clutch. One day it'll seize solid, BTDTGTTS.

Yes it's intermittent. Not always. I'll get a mechanic to look at it at next service.

Then I think jimc with his sprag clutch could well be right.

Please let us know what the problem was.