My head hurts: US Spec 2020 GTS300 HPE Evap System Mod
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Enthusiast
2020 GTS300 HPE Super Sport, 2005 GT 200L, 1978 P200E, 2010 S50 4V, 1966 Blue Badge (Polini), 1965 90 (Malossi), Honda Helix, Italjet Velocifero
Joined: 10 Aug 2011
Posts: 80
Location: Huntington Woods, MI
Sat Nov 21, 2020 5:17 am quote
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!

Last edited by rmwill on Sat Nov 21, 2020 5:39 am; edited 1 time in total
Enthusiast
Stella
Joined: 28 Jan 2012
Posts: 59
Location: USA
Sat Nov 21, 2020 5:31 am quote
It will go out on its own soon. It isn't as critical as a carbureted bike.
Veni, Vidi, Posti
2008 MP3 500, 2013 BV350, 2020 Vespa Sei Giorni
Joined: 13 Oct 2012
Posts: 8708
Location: Ashburn, Va. Home to the Internet
Sat Nov 21, 2020 6:13 am quote
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.
Hooked
2020 Vespa GTS Touring 300
Joined: 16 Feb 2020
Posts: 153
Location: Northern California
Mon Nov 23, 2020 10:01 am quote
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:

http://modernvespa.com/forum/post2437692?highlight=#2437692
Hooked
2020 GTS 300 HPE
Joined: 27 Sep 2019
Posts: 259
Location: San Francisco
Mon Nov 23, 2020 10:12 am quote
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.
Hooked
Primavera 150
Joined: 17 Sep 2017
Posts: 466
Location: Long Beach, CA
Mon Nov 23, 2020 12:03 pm quote
mayorofnow wrote:
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.
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.
Veni, Vidi, Posti
2008 MP3 500, 2013 BV350, 2020 Vespa Sei Giorni
Joined: 13 Oct 2012
Posts: 8708
Location: Ashburn, Va. Home to the Internet
Mon Nov 23, 2020 12:11 pm quote
bosco12 wrote:
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:

http://modernvespa.com/forum/post2437692?highlight=#2437692
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
Veni, Vidi, Posti
2008 MP3 500, 2013 BV350, 2020 Vespa Sei Giorni
Joined: 13 Oct 2012
Posts: 8708
Location: Ashburn, Va. Home to the Internet
Mon Nov 23, 2020 12:13 pm quote
mayorofnow wrote:
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.
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.
Sponsor
Joined: 16 May 2011
Posts: 403
Location: Austin on IH35
Mon Nov 23, 2020 1:02 pm quote
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.
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