Modern Vespa

I can't figure this one out.
2008 GTS 300. No evap stuff. Battery is good. Starts and runs perfectly from cold. Did 90 miles yesterday and it ran perfectly. Came to put it away and it wouldn't start. It would crank, light's were fine but wouldn't fire. This only seems to happen when the engine has reached full operating temp.
Fuel starvation?
I'm stumped.
Any advice would be appreciated.

It does sound like a fuel issue. You can confirm that by seeing if it starts with the help of some starter fluid sprayed into the air intake.

The odd thing is, if i let the scoot cool for a bit, it fires right up.
I can't figure out why?
Thanks for the input.

It's probably vapor lock.

If it were a classic scooter I would say it was probably flooding. Not sure if that is possible with an auto.

When you first switch the ignition on (when hot) do you hear the fuel pump prime?

Also, does this problem occur immediately after you stop when it's hot, or a few minutes after?

The pump primes when switched on. The fault happens when i have been away for a few mins - say after parking the scoot up, walking through the house while taking my kit off or calling in at the shops for some stuff.
If left to cool it fires up no probs.

Next time this happens try popping the gas cap off and listen to see if you hear a hissing noise as the air rushes in. You might be having a fuel vacume problem, I have read about here on MV.
Do you have the Evap hose removed or cut? and the proper ends blocked off?

OK. I'd be suspecting the ECU or coil/HT leads. The engine gets hottest a few minutes after stopping after a long ride - and the ECU is now mounted on the throttle body, close to the very hot engine[1]. So any connection to the ECU, or dry joint or heat-sensitive component inside it could be at its point of failure.

Or it could be the ECU objects to a sensor input that has been disrupted by the heat.

It's still under warranty, so time to take to a clueful dealer.

[1] I always thought this was madness...

Nice one Jim. Will try to get the local dealer interested. Sounds as though it might be what you have said.
Of course they now have to replicate said fault....

Well - i thought the problem had vanished, but it seems to be doing it regularly now. Definitely temperature based issue. When cool it starts every time. Calling dealer on Monday. Hope it's a quick fix...

I'd start with simpler things first.

You removed your evap stuff...maybe you did so in such a way that your getting heat/vacuum related issues. Try removing any plugs you've put on and see how it goes....just to track the issue.

As other's said, it might also be your fuel tank is not venting. Is your tank close to empty. When you open the cap does it give a loud hssssssssss?

Try those things first. They are cheap and easy to check.

Euro spec mate. No evap stuff.
The fuel pump shuts down when hot. Runs fine when cool, stop, switch ignition off, switch back on, no fuel prime sound, no fuel from pipe when cranked, wait for it to cool for an hour or so, press starter and scoot burst into life.
Like Jim says above - it's pointing toward a dry joint.
Cheers anyhow!

Time to get the multimeter out and see if the expected voltages are present on the "Fuel injection loads control switch", aka injection control relay.

I checked for resistance across 35 - 36 and my meter read 0 ohms and i think it should be 40 - 80. Not sure i read it right. That was with the relay pulled from the carrier. I did see something in the manual about applying a 12V supply.
Any tips?

I tread carefully here - from your reply I'd suggest you get a friend you know understands electrics to test the things you want tested. Not a put-down, but an 18-page explanation is not what I want to write, and not what you want to read.

No worries Jim. Not all that sharp regarding sparks anyway. I still reckon you were right with your earlier post about the dry joints. When the scoot fails, you can still here the fuel remote relay pull in, even when the fuel pump doesn't prime.
Just weird. I wish it were something nice and simple...
But, it's still under warranty, so the dealer can sort it tomorrow.

Just read on the UK GTS forum that a few 300's have had the same issue and the fuel pump's were the culprit.
I hope it's that simple.

I had the same problem with my 09 GTS250ie. Turned out to the fuel pump.

I'd love to have a 'duff' fuel pump in my hands to find out what the real issue is with them.

So would I! I took it to Vespa of Newport Beach and they did it for me. Though I am still having the backfiring problem... very frustrating.

Would be handy!!

Dropped the Vespa off this morning and by all accounts there is a service bulletin out about the fuel pump. Known fault then.

The dealer has loaned me a Gilera Fuoco 500 to rip around on while the warranty is being processed.

Bit of a culture shock!! 3 wheels...

Just got the Vespa back. God - i missed it! Just settling back into the seat brought a smile to my face.
I can honestly say i have never gelled with a vehicle the way i have with my scoot.

I'm getting close to naming it.......

Paul, is your 300 back to normal again after the service?

Yes mate. Sweet as a nut. Stop start traffic at rush hour, a fueling stop and a good thrash home. Coped with it all admirably.

My brother had exactly the same problem.
Fuel pump replaced on his 300 under warranty and no all is ok.

Glad to hear it all panned out OK.

I wish i could have got the old pump for you to have a butchers Jim - but as it was a warranty job it's got to go back to the factory...

Understood - that's one gotcha with many electrical warranty jobs, you can't have the old bits back to see exactly what went wrong.