Modern Vespa

I have a Vespa gts 300 2015, and recently the Scooter has been cutting out, it does not happen all the time, you could be just ridding along and suddenly the Scooter will just cut out and I come to a halt and the efi light comes on,I turn the ignition off for a few seconds then back on and the scooter starts up ok the efi light goes out and everything is ok,I can ride it for a couple days all is fine then it will happen again just out of the blue, I have noticed that when you remove the fuel cap there is a whoosh of air as the fuel cap is unscrewed, could it be a fuel venting problem?

Hi Nigel, it's normal to get a whoosh from the tank when you release the fuel cap. You should have positive pressure in the tank.

Something to check is the battery lead terminals. Cutting out randomly is a key symptom of one or both of them being on the loose side. Also check the spark plug cap is fitted tightly to the spark plug.

I had a situation where the engine would cut out like that intermittently. The dealer ran diagnostics and eventually it revealed the problem to be the fuel injector. Installed a new one, problem solved.

I have checked all connections all fine, but I have read that the engine Stop Switch can play up causing this problem, so I am fitting a New one to eliminate this. If it still plays up I will take the scooter to a Vespa Dealer to get them to plug it into the diagnostic machine.

Gotta love that 8k. The help on scooters is horrible.

Apparently very common on 300's. - with various reasons.

It happened to me centre lane on the M25 - cut out for about 3 seconds, and then went again.

Not nice at 60MPH surrounded by traffic. You can't even pill the clutch in and coast

If the 'whoosh' when the cap is opened, is an inward rush of air, then no, - it isn't venting correctly.- the tank should not be under vacuum.

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Hi tenders, the fuel tank on carbed bikes are vented and should not build up any significant pressure or a vacuum. Many, fuel injected bikes, but not all, run with minor positive pressure in the tank using a split valve shut off system. This pressure should not be anything more than tiny, but will quite often give a small whoosh as you open the tank cap. A big whoosh might mean something is amiss.

Content deleted by tenders. A forum where management/moderators repeatedly quash and delete well-intentioned, constructive concerns about governance issues raised by multiple users does not deserve my participation.

I also have a 2015 and this happens rather frequently when it's just started and within 10 minutes after starting. No need to turn off ignition / turn back on. I just pull in the brake and hit the starter while still driving and don't miss a beat. There is nothing mechanically wrong with my scoot - it was checked out under warranty. Iust doenst like warming up.

Well I have fitted a New Kill Switch, rode to the fuel station put fuel in rode 1/2 mile and it cut out (not kill switch problem then), efi light came on stopped turn Ignition off then on again started first time and rode 10 miles no problem. I was wondering if it is a relay causing the problem, as once the ignition is turned off then back on again it resets its self ? or the injector ?