Modern Vespa

I have changed the broken stator in my MP3 500 (2012) but after reassembling everything the engine doesn't start. For me it seems like there is no spark on the spark plugs.

Does anyone have an idea where the problem can be?

First guess have you checked the fuses, also if red light is on could be immobiliser

Yes, I've ckecked all the fuses (they're all good) and also the red light is not on.

the dreaded hidden 30 amp fuse? and not the spare that's attached to it.

Where can I find that one?

Here below

Hidden Fuse DONE - pictures and all

I foung the fuse but it's completely OK, so the problem must be somewhere else...

Some good places to look and test in thread below

MP3 500 no fuel and no spark questions

Could be a problem with ignition (phase) sensor. Quite unsure what's the English for it, but that thing is located on stator and gets a signal from magnet (rotor) for spark timing.

Don't you know what exactly can be the problem regarding the ignition sensor? The whole stator is new so I suppose that the sensor should be OK.

Is engine turning over but not starting, if yes check fuel is arriving

You say "seems like there's no spark" - well, is there or isn't there spark?

And as above - is there fuel being squirted out of the injector?

The sensor might be misaligned, damaged, rotated or so
The cable could be damaged
The connector could be disconnected or damaged

So check everything you can regarding that sensor. And yes, try to find out whether you have spark or not.

This is a very valid comment. If when installing the stator with the incorporated crankshaft sensor it was not in the exact place or had some damage/disconnected, it could explain the symptoms very well.

We have checked everything with a friend who has better knowledge about the motorcycles than me. We found out that there is no spark and also there is a problem with fuel injection. When we had injector out and were pressing the starter button, it injected the fuel only 2-3 times and not more.