Modern Vespa

I have read every forum post on the subject. I overfilled my 2020 GTS300 Super Sport and the CEL is now on. I would like to do the evap mod, but it seems every post about the removal actually being done is for an earlier non-HPE bike. HPE owners ask the same question, and pre 2020 owners reply: "Works Great!".

Have any actual 2020 HPE owners successfully performed this modification? Is there a way of drying out the canister? Thanks!

It will go out on its own soon. It isn't as critical as a carbureted bike.

Since the EVAP system now sets codes when it has a problem, (overfill is a problem) it may not be removable without the light being on all the time.
The old system did not set codes if it had a problem.

This has never happened to me when I overfill so I wouldn't be in a big rush to fix that directly.

Perhaps its an indication that something else is out of sorts like the O2 sensor. In the meantime perhaps you can try the procedure outlined in this post to kill the service light:

https://modernvespa.com/forum/post2437692?highlight=#2437692

I've put over 12,000 miles on my HPE and have filled the tank to-the-brim many dozens of times. It's never caused me problems.

That's just an anecdote of course. Perhaps I've been lucky, or perhaps you've filled even more than I have, but I haven't had any problems with the evap system - certainly none that triggered the check engine light.

There is something called a "volet" in the system that captures the overflow before it gets the the evap canister. #14 in the pic.




If there is fuel in the volet, the vacuum developed in the tank as you ride will pull it back out and into the tank. After that, just air from the evap canister (as normal).

I left the volet in place when I removed the evap canister on my 150. That way I don't get gas on the ground if I over fill.

It is a known problem, Piaggio's fix for now is ride till low fuel light comes on then fill with 1 and 3/4 gals of fuel. That info was provided by SDG

At some point it will cause issues, do as you wish. If you start having running issues like stalling or hard starts suspect a saturated EVAP Canister.

the CEL light is from the oxygen sensor detecting an over-rich condition due to the excess fuel. Over-rich from the EVAP liquid gas, not normal vapors it usually deals with making its way thru the engine.

The good ole Italian tune up usually clears the code and symptoms.....do a good long wide open, high speed run. That'll pull vacuum on the EVAP and clear the liquid and fumes out.

That is usually called a "rollover valve".

And my experience has been as AF1 described. The system is designed to draw liquid gas out of the charcoal cannister. It should disappear given a bit of time.

No. There is not a valve in the volet. It is simply an empty ball. The rollover valve is the check valve - #6.