Hi,
I'm bringing a Vespa ET4 125 Leader back to life after it had been sitting unused for quite a long time. I've already done quite a bit of work on it and finally managed to get the carburettor sorted out, so the engine started behaving properly from the fuelling side. Unfortunately, I've now run into an ignition problem.
At first, the scooter would start and run normally when cold, but once it warmed up it would lose spark / cut out. After cooling down, it would start again. That made me suspect the stator/pick-up, so I replaced the complete stator.
After replacing it, things actually got worse — now there is no spark at all, even when the engine is cold.
So far I have checked the following:
- the immobilizer warning light flashes once and goes out after turning the key, so the key is being accepted;
- I added a direct extra ground connection from battery negative to the engine — no change, still no spark;
- resistance of the new stator pick-up measured to ground is around 135 Ω;
- while cranking the engine, the same pick-up output produces AC voltage — the meter briefly showed more than 12 V AC;
- I swapped the HT ignition coil for another one — still no spark;
- the spark plug/cap has been checked against ground — no spark;
- the pin layout in the old and new stator connectors is the same;
- I have not yet swapped the CDI/ECU.
Before replacing the stator, there was spark when the engine was cold. The spark disappeared completely immediately after the stator replacement.
At this point I'm still wondering whether the new stator/pick-up is faulty despite the measurements, or whether the issue could be with the CDI/ECU.

Regards
Glaniu