Modern Vespa

Hi All,

New to the group, hope to be able to contribute but need your support this time.

I have just received a Vespa GTS300 supersport and it won't fire up. The starter motor turns over fine (so not a kill switch issue) but there is no firing of the engine whatsoever.

The bike was shipped in a crate and has been in the box for 3 months but when it left the dealership was running fine. The bike was quite dusty coming out of the crate (in case it has any bearing)

There is gas in the tank, power in the battery and the starter turns over but just no firing (not even close).. really gutting tbh.

Any help would be really appreciated.

Battery---get it charged

If not the battery...check that the spark plug cap is on tight.

make sure the spark plug cap is on tight, does the fuel pump buzz?

thanks - battery is fully charged. will check spark plug cap and listen for fuel pump too.

Kill Switch?

Do NOT 'give it a bit of throttle' - it won't start, by design. Leave the throttle alone.

That's right, there is the automatic choke.

ok...

have filled with petrol, recharged the battery, checked the spark plug connector and it still won't fire up..

I guess its something more complicated like fuel pump or dust in the carburetor.

Can you hear the fuel pump prime for two seconds when you first switch on? If not, check all fuses are sound and securely in place. If they're OK, check the 'ignition loads relay'.

thanks JIMC

The fuses all look good.

I hear the fuel pump relay click but nothing after that. what sort of noise should i listen for?

i traced the fuel lines one doesn't seem to be connected to anything..

see attached photo

where should i plug the other end?

Nowhere. It's the overflow

Do you only hear the relay click, but not hear the fuel pump prime ('whirr') for two seconds after you first switch on? If so, either a connector has become adrift or the fuel pump is seized.

there's no whirr. I've got a yam 125cc and can hear the pump prime on that scoot. will check the connections on the Vespa. The bike's only gone 5 miles so i really hope the pump hasn't seized

Thanks for the tip

Now you said in your first post that the scooter when it left the dealership was running fine. How far did you drive it to your home?
And if it is brand new just take it back to the dealership and have them sorting out the problem.

OK.

Let's start at the beginning - what flashes (if any) are you getting from the code LED when you first switch on, and does it stay on or go off?

PeterCC

it says 5 miles on the clock. also the dealership worksheet checklist shows all checks complete including starting and running it.

the problem with taking it back to the dealership is I bought it in the UK. I live in the Cayman Islands so had it shipped here (it took 3 months!). I'm in contact with them but they're on their holidays (understandably) now.. Also the local dealership shut down 6 months ago which is why i had to get it from the UK.

jimc

thanks for assist..

key in. red led flashes. check engine light on, abs light on, oil light on. lights front and back on. fuel gauge full. (battery checked and at 97% (brand new))

Engine light and oil lights go off

kill switch off and side stand up. check
hold break, push start.
starter motor turns over but engine doesn't fire. not even a hint at firing.

Spark plug connector checked
fuses checked

i don't hear the fuel pump whir though after the engine is switched on though..

You didn't say what number and duration of flashes the code LED gave, nor whether it then stayed ON or OFF.

Please give this info, it's a crucial first step!

jimc

using the master key, when i turn on the ignition the scoot led does;

one longish flash

followed by two short ones.

And then does it stay ON or go OFF?

goes off after that

Right. So we have a working immobiliser that turns off as it should. That's a very good starting point!

I strongly suspect some connector has come adrift. *If* the ignition loads relay is switching (you might be hearing some other relay?) then somehow its output isn't getting through to the fuel pump - and probably not to the coil or injector either - time to start testing with a multimeter to see where you lose 12V.

Although this circuit diagram is slightly out of date, it's near enough to give some clues:
https://manuals.wotmeworry.org.uk/Vespa/GTS300%20Super/GTS300%20Super%20Wiring%20Diagram.pdf

Fuel pump fuse?

I know you said they look okay, but have you pulled and reseated them?

Tipover switch?

Bad connector on side stand?

thanks to everyone for their help.

I'm pretty sure its a fuel pump issue - there is no smell of petrol at all when trying to start and no whirr from the fuel pump when i turn the ignition.

Although the local vespa dealership has shut down in cayman i have an italian who restores (albeit older) vespas coming round to take a look. hopefully by NY I will be able to enjoy the new beast.

Happy new year everyone!

I also had a issue with my sons 2020.I talked to the service manager at the dealer which is over a 100 miles away and he told me they have had issues with the pump and also the connector under the front part of the seat.He told me to lift the back end up and let it drop a few times and I did.It solved my issues that was similar to yours .I have put about 5300 miles on it with no more issues.

Happy new year to you too.

I see that your situation is a bit complex. At the dealership in the UK it was all fine but after shipment to Cayman Islands you have not been able to drive a meter with the Vespa. Turning it back to the dealer is indeed not a realistic option.

It seems to me the fuel pump issue is a realistic cause of your problem, although I would not know why a fuel pump would fail after a 3 months standstill.
I hope this Italian guy can solve the problem.

Unfortunately, it sounds like this "Italian guy" is experienced with working on pre-fuel injected scooters, i.e. no fuel pump.

Even so, it sounds like a matter of investigating the electrics, and he should be fine with that.

Just to draw a line under this..

I managed to find a local motorbike mechanic who isolated the issue to the fuel pump. Basically as the bike had been sat in a crate for 3 months the fuel had dried out and the residue had jammed the fuel pump. He cleaned it out and it works like new (which it is).

Next issue the seat won't open but that's a problem for another day

Hi there
Greetings from Western Australia
Great to hear that you have resolved the starting issue
As for the seat issue, I recall a lever should be in the glovebox that you can use if this type of issue occurs. However, I have not used it and maybe totally wrong😁
Cheers
Paul