Modern Vespa

I am driving my GTS-250 and suddenly it starts to cut out. I go to WOT a couple of times and it gets rid of the problem. Today it did it three times within one minute, then it went back to normal operation. I have checked the spark plug wire and it is secure. What else could it be besides a fuel pump? The gas is new and clean and it doesn't happen every time I ride. It is a little scary because I don't know when it will completely shut down as it has done at times. When it completely shuts down I coast over to the side of the road and turn everything off and then on and it starts right up. I though when a fuel pump dies it doesn't come back to life, at least that is the way I thought it works.

Are you getting a check engine light?
If so, it's worthwhile to have your dealer check the error buffer.

How fast were you going when it cut out?

There is no engine light. The three times it cut out today I was doing about 35MPH on Homestead road on the way to Trader Joe's at Foothill Blvd.

My first guess, then, wouldn't be fuel pump. I would guess kill switch before anything else. Fortunately, this one might be a quick remedy: mash your kill switch back and forth a bunch of times. Really punch it (with your fingers, not your fist) pretty hard, on and off. This will have the effect of cleaning potentially dirty contacts.

If the problem persists, I would revisit the spark plug lead. The issue isn't usually the cap coming off the plug, but the lead coming out of the boot. Sometimes the boot needs to be screwed back onto the lead, as there's an internal screw that goes into the end of the lead. Even if it seems solid, the connection can be iffy.

I would first check the spark plug cap.

Then fuel pump relay.

Intermittent problems are the suk......

R

8)

Jess, I think you may be exactly right. I notice that sometimes when I try to restart the engine it will not turn over until I flip the kill switch and then it starts right up. I look at the kill switch and it is off. It was like I turned the kill switch on, but I didn't. I will turn it on and off several times and see if that has any effect on the intermittent problem. Have you had this problem? I hope this is the solution and I think it is. Thanks for your help. Yes intermittent problems really do s....

Definitely sounds electrical. Have you checked the ground wire between the throttle body and air box?

Yep. Sure have. And it's been reported here a number of times. More importantly, though, it's really easy to test (and remedy), and so is the logical thing to try first.

I had the same problem, my scooter wouldn't go more that ten minutes without cutting out when I was going at speed -which was not much fun.

I cleaned the kill switch, replaced the spark plug, cleaned the air filter all to no avail.

One thing I noticed was that it kept happening repeatedly at the same places; usually either turning into a bend after a long straight or at the top of hills.

My missus thought that it might be because those were places where I tended to go from full throttle to no throttle (and then back on the throttle). She suggested that I adjust the idle as going from full to no throttle was stalling the engine. I told her she was talking complete rubbish, didn't understand engines and it didn't seem likely at all - but to prove her wrong I eventually adjusted the idle.

Invariably this has completely cured the problem and so I had to admit that she was right, as always, and I should obey her without question. I had dismissed the idle as it never stalled at the lights or when starting.

Ah, the secret to a Happy Life, my friend: Pick a good woman and do what she tells you!!

The battery is the first thing to check. Remove the terminal lugs, clean and then apply grease to all metal battery surfaces, tighten the terminals, and fully recharge the battery.

If you are really paranoid (like me), you can do the same to all ground connections.

Check the spark plug gap. It's supposed to be about .025 in., but it's usually about .017 in. on a delivered GTS. Fully screw the spark plug cap into the wire. Yes, they still make them that way (yuck).

when all else fails, remove the EVAP system.

These things are very reliable when everything is perfect. It just take a while to get them that way (from new).

Cheers and good luck,
Bob