Modern Vespa

This has happened 3 times this week and I'm worried about riding on the freeway. When I hit a hard bump, the motor cuts off. The LCD screen is still on, but I can't give the scooter any gas. I have to pull over, turn the RUN/OFF switch off, and back on to get it started. Is there something I'm doing wrong, or something that is broken? Any advice would be great!

Thanks!

Reggie

Can you reliability replicate this symptom by bouncing it up a driveway or other obstacles?

When it happens again, turn the bike off via the key, wait a few seconds and then turn it on to try starting again.

What happens if while the bike is running, you slap the kill switch a little hard to rattle it a bit?

I'm wondering if you have a loose or broken kill switch presuming there are no other indicators of the problem beyond the kill switch on/off.

Check the basics first, starting with a visual inspection. Verify the battery connections are clean and tight.

Ditto on the fuses, followed by making sure everything electrical is wired up and connected correctly.

I had a very similar failure a couple of years ago on the 250, and the problem was the transponder of the key that moved with some road bumps and stopped reading it, then it got more complicated and there were times that the bike simply did not start randomly, can be after a run, or first time in the morning, some times wait 5 minutes is enough, other times I check everything don't find nothing and starts, I changed the receiver and all problems are over.

The key transponder is only in play at first switch-on and start-up. After that it plays no part. You can test this by using the brown master key and once the bike is started, take the RFID chip out. The bike remains running.

So it can't be a reason for the engine to cut out once running.

Bad spark-plug cap or HT lead, worm out ignition switch, fractured fuel injector, faulty kill-switch from over-use could all be culprits.

Thanks for the response guys! I did check the fuses and there was one loose fuse that I pushed back in. I am in the process of changing out the spark plug and air filter. I'll keep looking to see if anything is still "off". I appreciate your help!

Ok. I replaced the air filter, replaced the spark plugs, checked for loose cables, pushed in a loose fuse, and it still happened. This time, when I hit the sharp bump, the engine stalled, and when I started up again, the check engine light came on. I rode home, got something to eat, took a nap, and when I got back on the scooter, the check engine light was off. I'll be taking my scooter to the dealer, but I would love to point them in the right direction. I don't know if a code was thrown or not.

Also, this only happens on sharp bumps going over 45 mph. The problem doesn't happen when going over railroad tracks or bumpy roads. It just happens when the scooter hits hard on a bump.

Totally stupid question.

Are you coming off of or unweighting the seat on the hard bumps? Could the seat safety switch be activating when you bounce?

That shouldn't matter once the tilt-lock is off.

My gut instinct tells me this is a wiring issue, specifically a ground/earth issue.

Could very easily be so.

I will check the wiring to see what is happening there.

I have a complete used wiring harness if yours is AFU I would be willing to let go reasonable $

Thanks for the offer! My MP3 is under an extended warranty so hopefully it will be covered if that is the problem. If its not covered I will be reaching out to you!

never mind the harness I have is for the 2008-2012 mp3 500,

i have had this issue it was the battery screws/terminal that were loose maybe this will help? check if your battery has a tight connection to the + -

Ok. I found out what the problem is. When I hit a hard bump, the kill switch turns the engine off. I didn't notice it at first because I was franticly trying to restart the engine. But today it happened and there weren't any cars around, so I could look at what was happening. When I flipped the kill switch back to run, I was able to keep going. So is this a bug or a feature? I'm guessing I need to replace the switch.