Modern Vespa

hi guys,

I have a primavera from 2015 whose engine is dying while idling upon twisting the throttle. It's an intermittent problem and happens occasionally however, sometimes it happens more frequently than other times. It never happens when the engine is revving up, only when it's idling.

I've tried nudging cables and pipings to check for any loose contacts with no success. Could anyone point me in the right direction to start trouble shooting this issue?

Thanks,

Tonio

Start with the simple. my first thought is check for leaks in any and all hoses. check or replace spark plug. Adding a fuel system cleaner, check air filters. and on and on, there are soooo many things that will affect a motors idle.

thanks for that

What do you mean by fuel system cleaner? Are you referring to an in line filter?

Air filters have been replace in a recent service. I will replace the sparkplug

You can buy a liquid that you add into your fuel tank and it helps to clean the engine and fuel lines.

Sometimes these cleaners are often added as standard into the premium petrol you can buy (Shell V Power, BP Ultimate, Esso Supreme etc).

Once you've added one of these products, try and go for a long ride with lots of heavy acceleration.

Spark plug is cheap and easy to do. When you remove this, take a picture of the end of the old one and post it here. People can tell from how the spark plug looks, how the engine has been running.

It's the bottom (away from the tip) of the 'white' insulator that's important to make judgement - just a side view only gives a hint.

I replaced the spark plug. Image of the old one attached. I'm not sure the picture is good enough but it looks a bit to black to me...

This one is more uplcose

That is a dead plug. It has expired, it is no more. It also indicates the engine is running very rich. Replace.

I'd also immediately be checking and adjusting the air/fuel mixture and the idle stop-screw:

Turn up the idle so the engine is running freely, and adjust the A/F mixture to get maximum revs. Turn down the idle stop-screw to a normal idle, and double-check the A/F mixture is optimised. It may take a few goes to get it spot-on.

I was told by the dealer once that these paramaters are only modifiable via software by a piaggio dealer. Are there real screws like the 2T models?

The A/F screw must be against the stop because that bike is running rich AF.

I'd assumed it's a carb'd model, my apologies if it's fuel injected.

I'd try and run a new spark plug for a few hundred miles / km and then pull it out again to see its condition.

On a fuel injection, the Vespa should automatically adjust the fuel for the available air, but maybe it's worth putting a new air filter in - maybe the current one is too blocked?