Modern Vespa

My GTS 250 ie has about 3,800 miles on it, three services done, filled up on premium gas the other night, a bit hard to start, wanted to die every time I stoped bike at low idle. Got it running, ran it hard, it ran well, now, it will NOT start up. Sounds like no spark. Lights on dashboard are strong. Pulled spark plug, couldn't find replacement on Saturday night, so I cleaned off the plug and re-installed. Still won't start. I can get a plug Monday, motorcike shop or Internet. The other distrubing thing is after about TWO presses of start button, goes from trying to turn over to completely dead. Tender charged it overnight and again it runs down after a couple of tries. Does that mean alternator is dead, or maybe battery. Battery is original, 4 years old, but attached to trickle charger winters. How to tell if it is alternator v. battery???

It sounds like your battery isn't holding a charge. The simplest thing to check is whether your battery electrolyte level is low. Remove the rubber battery cover (4 screws) the battery bracket (2 screws) and then unscrew each of the yellow plastic filler plugs on the battery. If you can see plates with no liquid covering them, then you should add enough distilled water to cover them again. It's pretty hard to see the min/max markings on the battery, but if you're feeling ambitious, go ahead and disconnect it and pull it out. Otherwise just get a big syringe (one came with our Showtime Rotisserie!) and fill each cell till the plates are covered.

If the battery does have electrolyte, then maybe at 4 years it needs replacing. FWIW, I had a bum voltage regulator on my GTS, which gave me a check engine light and dried the battery out. It kept dying at stoplights also.

Have you checked your spark visually? Try it after charging the battery overnight.

Sounds like a symptom I was getting,
I was told it might be the fuel pump.

But after close inspection they found that it was my fuel injector and my battery,
I got them both replaced yesterday and now my GTS is running like a new bike again.

4 years is a long time for the stock vespa batteries. I'd change it no mater what else is wrong with it.