Modern Vespa

My GT200 stopped running while going about 20mph. Ignition is fine. Battery is new and fully charged. Engine Turns when starting up but it just sputters. Oil level is good. More than enough fuel in the tank (always premium gas) What can be the problem?

It happened recently about a month ago, not long after I got oil/filter change, cleaned out air filter. That time, I just tried again in a few days and it started right up without any problems.

Any info/suggestion would be much appreciated!

Could you give us more info please. What kind of carburetor do you have? Do you still have the percolating system in place?

Carburetor and percolating system are all standard for the 06/07 model. Never had reasons to check it out.

I found this on the troubleshoot wiki. Should I give it a try?

Carb and Jet Cleaning 125/150/200 engines.

How would I know if it's the air filter, spark plug or fuel supply issue?

can you put it on the centerstand, feather the throttle and get it to take gas again? Try it a few times until you can rev it up when you turn the throttle.

What's your location?

My GT200 'burped' several times while riding before the fuel pump gave out a few days later. I'd also check the fuel lines for cracks and the filter for any possible dirt in there.

Good luck -

Los Angeles, CA

What are specific symptoms of bad fuel pump? I checked the fuel lines and they seem fine. I'll clean out the air filter later today. Thanks!

I'm not certain there are specific symptoms to a fuel pump failure except that mine did give me some 'hesitations' on the road prior to complete failure. Others may have different experiences with it, but there have been many fuel pump failures noted here.

There's a good wiki here on testing the fuel delivery system that perhaps you can try. The fuel lines seem to go bad early either from poor materials or the heat in the engine compartment. Mine died at barely 2K miles, though it had sat in a garage for some years.

The replacement hoses the dealer put in for me, I was too busy that week, are heavier and clear, as is the fuel new filter, really great for visually checking the fuel flow.

Despite my experience with the fuel pump, if yours is working well then I'd definitely look at a dirty filter or dirt in the carb. Those are easy to check.

Good luck on it!

Have you had your valves adjusted lately, could be exhaust valves closing after it warms up.

What you described could also be caused by a failed fuel tap/valve, or the vacuum hose that controls it.

Just pull the vacuum line and 'suck' on it, if the fuel does not flow the valve is bad.

Easy fix too but for dealing with the gas in the tank.

A common failure, so much I have a spare to carry on long trips.

Good luck with it.

R

I think you might be right. Both times that this has happened were shortly after starting the bike.

Take it to your local Vespa dealer and have an ultra sonic carburetor jet cleaning. It should be about $40.

UPDATE:

I started with checking the spark. As it turns out, my last mechanic put in the wrong spark plug, a shorter one used in buddy scooters. I replaced it with correct plug but still not starting. then i cleaned the air filter.

I brought it to a new mechanic to get the carb checked out and the jets cleaned (after I failed to open the carb myself bc the screws were stripped), but he told me that the "petcock" is not working. Does this make sense to everyone? Is this in any way related to having a wrong spark plug in there? He says he hasn't touched the carb yet but petcock seems to the issue. Thanks!

The 'petcock' or vacuum operated fuel tap, can fail. Quite common, as the many posts on the subject here can attest.

This sounds like a fuel tap ready to go. Last summer my 2006 GT200 died going up a hill! I was so glad no one was behind me. I restarted and made my way home. Didn't use the scoot for the rest of the weekend. Upstairs neighbour commented on the strong smell of gasoline in the driveway. Went to start scoot. Bone dry. Bought small amount of gas and added it, only to watch it piss out the side of the carb.

My dealer came and picked it up and replaced the fuel tap. I also had him detach the evap system. I had bought the scoot used from him. He said the scoot was better than it ever was. Haven't had any stalls or roughness since.