Modern Vespa

I have noticed that sometimes when I am ready to start moving, I give the mp3 500 the throttle nothing happens and it just idles. I can do this several times and no go, then give a little twist again and off I go. It doesn't do it all the time. Any ideas?

Possible seat sensor problem, bit off help below, look at jah post also

How to start a piaggio mp3 500 with defect seat sensor

Is the tilt locked?
I got an occasional tilt lock red light & unresponsive throttle if the battery is low volt [one bad cell]
Unlock/lock a couple of times cleared it
the battery was bad
No reoccurrence with a good battery

Yes the tilt is locked and I was sitting in the garage on a level floor. As I said it has happened only a couple times in the past year.