My 150i started running rough and throwing an engine light a few weeks ago. After checking the air and spark portions of the fuel-air-spark equation I decided it was a fuel problem and decided to troubleshoot the injector.
First I pulled the injector off the throttle body turned on the key with the injector pointed into a can. No gas. Then I pulled the fuel line off the injector and did the same thing. GAS! And plenty of it! OK, the fuel pump is working.
Next I checked injector function by removing it and connecting it to a 9-volt battery on the workbench. I could hear the injector click and I could shoot carb cleaner through the injector with the circuit completed. So the injector was good-to-go.
Then I used a 12-volt check light to see if the injector was getting power. It was, at key on and start button pushed.
I was stumped. I had power, fuel, and a functioning injector. But it wouldn't work when it was all connected to the bike. I decided to look at the wires going to the injector. Maybe the negative was bad or broken. And sure enough, it was. The negative wire was broken, right at the connector. No way to rewire it, but I found a matched connector on Amazon. Wired it in this morning and "VROOOM!" Yay!
In any event, you might have a similar problem some day. Maybe you can use one or all of these tricks to isolate it and get your scooter back on the road.
From Amazon.
Alligator clips: 12pcs/20in. Alligator Clips Electrical with Wires UL1015/18AWG, 6 Colors Jumper Test Leads Set, 1.77in. Clips Soldered with Wires- EDGELEC
Connectors: 8 Pack Fuel Injector Connector Pigtail Wiring Plugs Clips Cut Splice for Bosch EV1 Any RC Replace EV1 OBD1