2.3. If the engine is not started even if the starter works normally

1. Check availability of fuel in a tank.
2. Check for existence of humidity on electric components under a cowl. Switch off ignition, then wipe damp components with dry fabric.
3. Apply a water-repellent aerosol (WD-40 or an equivalent) on electric sockets. Pay special attention to the socket of an electrical wiring of the coil of ignition and wire of high voltage. Diesel engines usually have no such "disease".