Modern Vespa

Vespa S150 i.e 1700 miles on the clock.

Anyway, cutting a long story short, ever since a couple of months ago, after an overfill, the Vespa was chugging real bad. After doing everything possible myself, in way of changing the plug, checking all wires, taking out the Evap charcoal canister and blowing compressed air in it for ages, running berryman thru it. The problem was sort of fixed. It was very much ride-able occasionally it would stutter and stall at idle, but I figured well there's probably still some fuel somewhere in the canister that hasn't fully dried itself out.

Anyway the other day, it seemed to get a little worse, and i thought the heck with this. I'm no longer enjoying riding this, cos of this occasional stutter, and sent it off to my local Vespa dealer to get it on a diagnostics machine.. ONCE AND FOR ALL !!!!

After two days with it, he just said, they checked the fuel pump, and it was not faulty, nor is my VIN on the recall list... So they've just reprogrammed the mapping, and it'll be $75.

Doesn't make sense to me. Not collected it yet, but don't want to hand over $75 only for the stutter to come back and a few days.

I don't know what to tell you about your service and cost.

If it does start doing it after you get it home loosen the gas cap and listen for a rush of air. If you hear it try riding with the gas cap loose. If it stops then it is your evap crap.

To figure out what part of the evap system it is re-tighten your gas cap disconnect the evap canister hose at the roll over valve. Temporarily plug the hose going to the evap canister with an appropriate size bolt and leave the nipple on the roll over valve open. If it stops it is the canister. If it still does it you may have a sticky roll over valve so next try disconnecting the hose that goes between the roll over valve and the gas tank and just leave it open.

Or you can just eliminate the whole evap system (they are only on US bikes anyway) as many here including myself have done. Plug the hose that goes to intake manifold with an appropriate size bolt and hose clamp and leave the hose coming from the tank open reroute it toward the ground.

I agree with sticky. Its the evap system.

And as far as the dealership charging you $75, id say why shouldn't they? You brought the scoot to them, asked them to look for a problem, they did a service- the investigation and the remap- so why shouldn't they get paid for their time and effort? They could have said "We did this and this and this" and billed you for three hours. I think they were being honest with you and let you off easy.

exactly.

They all need a remap - they're delivered with a map to mollify EPA and CARB. After that? Re-map with something that works better; 'Oh, it's an update'.

But please rip out that Evap Crap if it's even suspected of causing problems.

Sticky didn't say the problem was the evap system. He told the OP how to troubleshoot whether the evap system (tank venting) was the problem. MV is full of accounts where someone complains of a rough running or stalling issue, pulls out the evap system based on the advice of others, and the problem is not solved. Diagnose first.

Sure looked like it was his #1 best guess though.... and he did say check first if the tank gives you a whoosh. Which tells you it is the venting system.

That's right. It tells you IF it is the tank venting system - or not.