Scooter hard to start cold: automatic choke
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Applies to: Vespa LX 50 and other carbureted scooters with an electric choke
Symptoms
- Hard to start cold, fine when warm
- Runs rough and rich after warm-up
- Stalls at idle for the first few minutes
Why it happens
The electric automatic choke opens as it heats up. If it fails stuck closed it runs rich when warm; stuck open it won't start cold.
How to fix it
- Check the choke's resistance with the engine cold.
- With the engine running, check for voltage at the choke connector.
- Check that the plunger extends cold and retracts warm.
- Replace the choke unit and clean the carb's starter jet.
Tools and parts
- Multimeter
- Auto choke unit
- Carb cleaner
What the factory service manual covers
Fuel system: auto choke test values, carb service. The full procedure, specs and wiring diagrams are in the factory service manual for your machine.