Modern Vespa

The good news is, this didn't happen in the middle of a recent 900 mile trip, but instead only 17 miles from home. ( Still, that was a $155.00 tow)!
The bike stopped running going about 35 mph. Doesn't want to restart. It emitted a continual high pitched tone--(the one you hear briefly when the tilt lock is engaged) while we were trying to restart it. When it did start, it ran very rough--would not move the bike forward an inch.
We checked the battery connections, all the fuses, and all was well there.
My charging system monitor showed the battery at 10 instead of 12.5, though I had been trying to start it for a while when I noticed this ( this is an aftermarket add on item, not stock).
But now, with the battery charged up, it starts and sounds like it would run.
Could all this be from a weak battery? I have had no indications the battery was weak, though it is the original battery, run now since March of 08.
It is no doubt due for replacement.
I suspect it is probably something else, and now, with it running again, the mechanics will have nothing to work on, but I am left with a bike I do not really trust ( it died on a ride a month ago, but restarted).
Any ideas would be appreciated. I will have the battery checked, to cross that off the list. And plan to buy a new one anyway.
My buddies hung around till the tow truck arrived, though they missed their breakfast--a good bunch of guys!

You say you checked ALL the fuses? You checked the one under the engine access panel in the pet carrier area?

Search hidden fuse of you haven't heard of it.

Wayne B

Seat sensor? This sounds like the exact symptoms you get if you try to rev the bike whilst not sitting on the seat.

Well. it must be the battery--if not it must be the charging system.( Not sure which) My fully charged battery (12.2 volts) went down to 8.5 on a 5 minute ride. I did check the "hidden" fuse--that was good. And yes Jim, acts exactly like the sensor under the seat was not activated. Until I charged it up.
Perhaps all these things could go screwy if the battery was down?
I unfortunately never found a clean way to display my charging system monitor, so it lives under the seat where I look at it from time to time-- I think I will renew my efforts to get it where I can see it. It would have saved my ride and my money today.

AAA Plus RV covers motorcycle towing, too. up to 100 miles, up to 5x/year. ~$120/year or $150 for you and your spouse. one short tow and it's paid for itself...

Ah, yes, a duff charging system would produce the same symptoms, probably due to the seat sensor not getting enough volts - or some other part of the associated circuitry.

So it's a duff regulator (but they usually just over-charge) or duff stator - or stator wiring connector. Cheekythomas usually removes the three-yellow-wire brown-coloured connector between stator and regulator and crimps the wires together at PDI - I would make this connector the first thing to inspect.

Toshi--point driven home--I am in for that service.

JIm, the battery bounced back to 11.5 volts within a 10 minute rest, so it seems the battery is not the culprit, but as you said, the charging system.
My illustrious mechanics will have to have a go at it on Tuesday--my extended warrantee continues to pay and pay. But runs out next March.
Think I will sell the bike about then.

The buyer will have the benefit of a fully fettled bike, lucky guy!

Rob, how old is your bike and how many miles do you have on it? I'm thinking about the extended warranty when I pick up my MP3 500. Do you think you'll buy another MP3?

I have close to 8000 miles on it. I have come out well on my extended warrantee, but it is an in house warrantee that covers changing tires and almost everything, all the services. And I bought it primarily with the dread front end issue in mind. The Piaggio warrantee was not favored by my shop, though I warned them they could get stung by that notching front end business. So far, I have not had that issue.
I would consider another 500. I love many aspects of it. I feel very comfortable on it. Then again, I could be tempted by a Mana too. I will sort that out when the time comes I suppose.
After maybe 10,000 miles, do you keep it till it drops or trade/ sell it?
Bound to hit the front end jackpot sooner or later.
Not sure I trust a reworked front end done locally, though it might be just fine.

Word from the mechanic is that there was a bad connection to the "hidden" fuse, resulting in a melt down of the fuse ( thought I checked the fuse!, But did not have my glasses on) and the starter relay, which will need replacing. Be interesting if there are more issues when that is fixed. I hope not. I have to wonder why this happened in the first place.
With the fuse whacked the whole system would not be charging. Explains the weird behavior I suppose.

I had to replace my starter relay (under warranty) a few months ago with similar symptoms. It's the design of the fuse holder and the exposed position of the relay that contribute to the failure.

https://modernvespa.com/forum/topic44194

Pictures:
http://www.wotmeworry.org.uk/fuoco_solenoid/