Modern Vespa

So I was riding down a road doing about 35 to 40 when all of a sudden it just stalled. I was just getting ready to stop at a light when it happened so I just coasted to a stop and tried several times to start it before it started back up. I then rode across the street and it died again while I was going into the parking lot. Let it sit a few minutes and it started up. I hadn't ridden in a couple of days so I thought it might be the battery. I have already disconnected the evap a while back. Since it started back up I went ahead and rode it around a lot today and then when I got back home I tested the battery with my multi-meter and it read about 16v. Any other suggestions on what caused that out of the blue? I never had it die since I disconnected the evap on it, although it takes a couple of pushes of the button to start about half the time.

Check the fuel line for leaks. If it's the old original fuel line, it may be cracked and due for a replacement if you haven't done that already.

Also check the clamps where the fuel line connects to make sure they are tight.
After experiencing a very similar problem one dark and stormy night (I kid you not), I found the clamp on the tap end a bit loose. I tightened it up and the problem never returned.

That voltage is too high. Your battery should only read just a smidge above 12V. If you were running the engine when you got the 16V reading, then your regulator is overcharging. The spec for regulator output on an ET4 is 14V to 15.2V. You may have a bad regulator or a bad battery (or a bad multi-meter).

Checkout this topic for a description of how to diagnose charging problems: Dead battery AFTER riding. (Post 958745)

-Craig

Ok so I took it for a ride today to see if it might be the battery getting low. I rode for about fifty miles and came home. About two or three hours later I went riding again. This time I stopped at a friends house and when I came out after about 30 minutes it wouldn't start. Tried starting it for about five minutes and nothing. Then all of a sudden it starts and rides home perfectly. When I got it home I cut it off and immediately tried starting it again and it started without any problems. It seems really unpredictable. Almost like it's the starter or something loose. When it doesn't start it just makes that whirring sound like it's not catching. I haven't checked the voltage on the battery while it's running yet. Somebody got a clue what is going on?

Check the cap on the spark plug to see that it's not loose.

That (along with other things) could cause the scooter engine to stop in mid-ride.

A low or bad battery would cause starting problems, but I don't believe it would cause you scooter to stop on the road.

A starter bendix that doesn't always engage properly would cause the whirring sound, but also would not cause the scooter to stall.

This type of problem solving over the net often involves a lot of back-and-forth to get a proper diagnosis. Sometimes it's a combination of things. Patience.

Start by eliminating the simple causes first.

BTW, did you check your fuel line?

I looked at the hoses but I don't know which is the fuel line and which is the one that runs to the evap (which is disconnected from the carb btw). I'll check the spark cap. I've got a new plug for it but it looks very difficult to get to to change it. I'm thinking that the time it died while I was riding yesterday might have been when I was slowing to stop and had very little throttle going for a little while there. Today it ran perfectly for about 50 miles of country road riding. Then started fine about three times before the problem occurred.

I think I must have two problems. I found a crack in the fuel line so that would explain the stalling but I still have the starting issue.

Ok, so I did replace the fuel line after my last post and then it seemed to work fine for a few days. Still kind of hard starting so I cleaned the air filter. Then I rode it around that day and it hasn't started since. I can't figure this out and I would really appreciate some help. The starter seems like it's working fine but it just won't start. Just chugs along like a car with a bad battery. I took the battery out and to the aurto parts store. They tested it and said it's fine. HELP!!!

Hi Dude.

I have had the same issue as you know Et4 Stalling at traffic lights UPDATE! and with mine it was a broken(and yes I know it has already been suggested, but our issues are so similar) cap ono the spark plug. Since replacing that I had no issues whatsoever. maybe the issue is somewhere there. hope that helps and you will get back on the road with no frustration soon

woocash

Thanks for the advice. I got in there and took the plug wire loose but it was so tight a fit that I couldn't get it all the way off. I put it back and tried it again, thinking that maybe it had not been connected all the way but it didn't work. I've got a new plug for it but I really don't want to drop the whole engine to change it. How did you do yours? I thought about just putting the new plug to the wire and looking to see if it sparks when I hit the ignition. If not then it must be the plug wire or another connection. Did yours seem to have miss while it was idling? Mine did before it just quit starting.

Ok, I changed the plug (a tight squeeze but only took a few minutes and didn't require dropping the engine) and now the bike starts. Now I'm just wondering what fouled the plug so bad. I'm thinking maybe the autochoke since the air filter wasn't too dirty when I cleaned it and I haven't messed with the mixture.

sorry for the late reply. It si tight but I didn't have to drop the engine down.

woocash

I have changed the sparlk plug yet again as the bike started stalling again. Just out of curiosity, what does your spark plug end with on the outside of the engine? does it have a little cap or a thread? I think there are to different types of that black cap on the wire that goes on your spark plug. I had do get one of those little metal caps that goes onto your spark plug before you put on the black cap (shit I am lost in this whole "cap" thing but I am not a mechanic so I write it as I see it, I'll better get some my camera and take some photos). I think this coused the issue in my case. But it was pissing down like hell yesterday and this morning as well, so my ET stayed pu. I am yet to test this theory. Will get back to you on this this evening.

woocash

Hmmm, probably best to take a photo if you can. I'm not sure what you are referring to. I think I should take off that autochoke unit and test it just to make sure. I have read here somewhere that it can get gunked up and cause problems. Not sure how to remove it, though. I can't find any screws holding it on.