Modern Vespa

I went out for a ride this morning ... about 90 miles in all. On the last leg home, the check engine light came on as I was braking, and then it would go off a few moments later. It did this several times as I approached home. I rode a good portion of the trip at 70+ mph ... not quite WOT, but almost. The same thing happened once before when I had a passenger. I've had passengers before and since that incident. At the time I blew it off as a fluke. But now it happened again without a passenger. Any ideas? Did I stress the engine? Everything seems ok ... temp was medium, oil level good, half tank of gas, etc.

All I can offer is that I had the exact same experience at 1400 miles and it has not happened since in the last few hundred miles.

*edit to appear literate

Not a problem unless it comes on and stays on even when you restart the scooter. Mine often goes on during very long downhill rides.

The first time it happened on my scooter it was probably around the same mileage as your incident. Now I'm at about 2200 miles. Yeah, I'm thinking its not that big of a deal ... yet. I kind of figured the same thing you stated: if the light stays on - especially after a restart, then I've got a problem. I did ride for a while this morning.

Thanks guys. Thumbs up to the both of you!

Check that the spark plug wire is firmly attached at both ends. The plug cap wire connection is often suspect... not screwed fully home. The cap screws onto the wire. Would account for your symptoms.

I'll check that ...

That reminds me of something else too: the first week I had my Vespa, the check engine light occasionally flickered on and then eventually it konked-out and wouldn't re-start. My Vespa dealer at American Biker offered to come pick-up my scooter, but first wanted me to check the battery connections. The positive connection screw came loose. It still has a tendency to loosen-up occasionally. Unfortunately, this time that was not the case.

So, two more things on the trouble-shooting list: loose spark plug wire AND loose battery connections.

Thanks ... thumbs up!

The following doesn't sound like your scenario - but if the engine check light comes on at high revs then check the regulator output - it may have a fault giving too high a current into the battery which will dry that out PDQ. Worth checking regulator output anyway, even if just to eliminate it.

Doesnt the controller store codes that can be checked when the check engine light comes on?

Yes - but that'll need a trip to a dealer that has a diagnostic unit, not all do in the US it seems.

You're a wealth of knowledge ... always so helpful!
That might not be my case either as later that evening I brought her out on the expressway and went WOT for 10 minutes ... no light. It seems to happen only under high stress over time - a couple of hours. Then again, it only happened twice thus far. I'll keep an eye on it and record it here if it happens again. Thanks, thumbs-up to both!

Wot does WOT mean?

Wide
Open
Throttle

Wide open throttle.

Wow - wot a fast response

Similar to WFO ( wide open) 8)

Unsure of what the attitude for reviving zombie threads is in this forum, but just for the reference of others having the same issue, this happened to me too.

The engine light was coming on an awful lot lately. I ignored it because "it will just go away" but, next thing I knew, I couldn't start the bike. I couldn't believe it was because of the battery since I had bought it less than 6 months ago and it was a good one (i.e., Yuasa brand). However, when I took it out and showed it to the mechanic, they realized immediately that there was no liquid inside and the battery had been fried.

Now the mechanic is asking for a $600 repair to replace the regulator. I'm seeing regulators for sale for $100 -- not sure if the quote is too much...

I had this problem, it was a dead sensor in the engine. It was replaced during it's service. The part was only £9.00. Gass silver machine gts 250

No problem if it's relevant. If the battery's fried - it's absolutely the regulator. $600 is far too much for replacement, which would take half an hour at most, including beer downtime.

I asked the mechanic if they couldn't give me a better quote -- they say because it's a GTS 250, they'd need to take a lot of stuff out. As for the price of the regulator itself, they say it's because they work with the genuine stuff.

I'll give other mechanics a call and see if they provide any lower quotes.

It's pretty easy to do it yourself - just the horncast, glovebox and floorboard to remove to gain access.