Modern Vespa

I have a sick GTS that stalled about 10 miles into a ride last night and would not restart. I and am puzzled as to what's wrong.

When I turn the ignition to on, the amber engine LED lights. The Code light is off. There is no attempt to crank when I push the start button (with the kill switch in the run position and flicked on/off in case there's a weak connection). Brake light works fine, and the headlight shines brightly even with the start button depressed (new battery last month).

This morning, after disconnecting/reconnecting the battery there's no change. The fan runs when ignition is on. There's also fuel dripping from the air filter. I removed the bulb to drain, and found that the fuel drip restarts when I turn the ignition on, and eventually stops after I turn ignition off. Coolant was _very_ low. It took around 1/2 liter to get it to the full line.

Not sure how relevant any other details are:
The scooter was sitting with 1/2 a tank of gas for 3+ years, and no new fuel was added. I have ridden 20-50 miles over the past month without incident. Last I'm back to riding after not riding the GTS for about 3 1/2 years. I've ridden about 30 miles on the old fuel that was in the tank and had not added new. About a mile into my ride I lost power for about 1/2 second and then power resumed as normal. I did not notice any loss of performance for the next 10 miles until all of a sudden the engine quit while I was riding at around 30 mph.

Since this failure, I have added a gallon of gas, brought the coolant to the full line with around 1/2 liter of G30 (great MV post by Jim on coolants!) and disconnected/reconnected the battery a couple of minutes later. But nothing has changed. Fan on, engine light, no cranking. There's no sign of a coolant leak on the floor.

Any thoughts?

The fan comes on when the vehicle is cold and cannot be started? Hmm...

Side Stand?
Have you checked the fuses with a multimeter or test lamp?

Can you hear the fuel pump whirring when you turn on the ignition?

The CEL coming on is OK - but it should shut off after a few seconds just like the fuel pump.

The code light should start flashing when you turn the ignition off again.

The fan running is not OK. Perhaps the ECU thinks the engine has overheated?

Check the connections to the throttle body?

Thanks GermanGTSDriver & jimc! The 7.5A Injection ECU fuse to the left side the pet carrier was blown. The electronics now act normal and the engine tries to turn over but is stuck.

With 250 ml of fuel having poured out of the air filter into a beaker while I was probing fuses, I imagine there's a flooded cylinder preventing rotation. Time or spark plug removal should get me past this.

If it is hydrolocked with fuel, you'll need to change the oil before running it again! Stuck injector?

At this point You probably should change oil and filter just in case of fuel dump in the crankcase
How many miles ?

A few years ago a GTS was delivered to my house with nearly the same conditions - It had sat for years and would not start with a new battery - so I was told my the owner. I took out the dipstick and it overflowed out with gas and diluted oil. The injector had stuck open, as far as I could tell, so it was replaced along with the oil, filter and spark plug. I checked the valves. Before replacing the plug, I shot a little oil in the spark plug hole and cycled it a few times with the starter. After all the work, it ran fine. I asked the owner to bring it back a week later to change the oil again. That scoot is still running good.