Modern Vespa

Hello all,

I recently was getting an engine light and hesitation on my 2009 300 GT (52,000 km / 32,000mi) which turned out to be due to low coolant level.

Changing oil and coolant to the right levels sorted this but just the other day the issue cropped up again with the engine light coming on and the engine stuttering only now it just happens when I have someone riding pilion. I checked the tire pressures and they are correct.

The symptoms at low speed were bucking and stuttering and on the highway the engine light stayed on until I decelerated to about 100 kph (60 mph) and then it rode normally until I exited and had to accelerate again.

I took the bike to a Vespa shop that has the diagnostic tool to read the error codes and they came back with the following two fault codes:

P0335-04 - which refers to the crank position sensor connected to the stator.
P0201-04 - which refers to the fuel injector and/or associated wiring.

They deleted the errors, tested the bike and it now starts and rides normally (with no passenger yet) so they told me to try it and come back if the faults reappear.

This should be ok for riding around town but now I'm hesitant to use the bike for longer distances, in case the issue crops up again and it breaks down.

Your suggestions are much appreciated.

Riding with a passenger will cause some additional weight which could affect wiring, pulling on it.

One thing that I have found is that the rear shocks are usually never adjusted for the loads, they are left in the default position, lowest preload setting. First thing is to check what they are set at and if set at factory default, increase setting to 2 or 3.

Thanks for this. I'm almost certain that I took the rear shocks up a notch when I bought the bike, but will double check for this.

At any rate, it worries me that the wiring is being compromised somehow.

Just an update to thank you for this advice. As it turns out, I had adjusted the rear shocks on my 200 but not on the 300 and indeed, with two up, the pet carrier is more prone to hitting the fuel injector assembly, causing the issues described.

After asking in another community, someone with my same year and model confirmed having the same issue that was sorted by raising the rear shocks to avoid the interference with the fuel injector when carrying a passenger.

I adjusted the rear shocks today and rode with a passenger and the issue did not repeat itself.

Thanks again!

That makes me concerned that you may have cracked the injector and it may fail completely at any time. I'd personally order a new one

The most likely place for the fuel injector to crack is the plastic interface piece on top of the actual injector. As it is plastic the break will be apparent immediately as fuel will be spraying.

The other intermittent possibility would be at the electrical connection at the fuel injector but this is below the plastic housing so housing would break first

I'm suspecting the connector.

We've had quite a few stories on MV about the electrical connection breaking - sometimes fatally, sometimes being intermittent. I'd have a good look at that!