OP
UTC

Hooked
2020 Piaggio Liberty S 150, 2016 Vespa GTV300ie, 2009 Yamaha C3
Joined: UTC
Posts: 161
Location: USA
 
Hooked
2020 Piaggio Liberty S 150, 2016 Vespa GTV300ie, 2009 Yamaha C3
Joined: UTC
Posts: 161
Location: USA
UTC quote
2006 Piaggio Fly 150, about 1900 miles on it. New to me, bought last fall and I've put about 700 miles on it. Fresh oil change this year and had it looked over this spring at a professional shop, no issues reported.

Up until the last 1 - 1 1/2 tanks of gas, I've had no issues with it whatsoever. However, about 150 miles ago, I noticed the scooter would lose power at WOT, like trying to get up steep hills, up to top speed on fast roads, etc. Initially I thought maybe I was hitting the rev limiter, but we were nowhere near speeds we'd hit previously; it was really a WOT issue, not a speed issue. The problem persisted and worsened; it was like I was losing power, but not stalling out. Roll off the throttle for a second and it was fine, away we'd go. Idles perfectly smooth, low speeds perfectly smooth, slow acceleration no problem. WOT = power loss.

Yesterday I decided I'd stick some Seafoam in it, just for sh*ts and giggles (I know I know, snake oil, but I figured it couldn't hurt.). I had a little under 1/4 tank of gas. But when I went to unscrew the gas cap, it was all I could it to get it off; the cap was on TIGHT, way tighter than I could have done myself.

Anyway, off we went to the store, about 25 miles RT, up to 60mph, no issues whatsoever. I highly doubt it was the Seafoam because it was INSTANTLY better, no issues. Which led me to think, maybe it's my gas cap?? I am by NO means a wrencher, but uncapping the tank was the only coincidence besides the Seafoam.

So today I figured I'd take it out again and see how she ran. OK at low speeds, but at WOT, same problem but back with a vengeance. I pulled over, uncapped and recapped the gas tank, turned for home, and made it back home with no issues.

Is it possible this is a gas cap/EVAC system issue? If so, can someone explain to me like I am 5 years old, how I can possibly address this (besides a new gas cap, I could never be so lucky)?
@jimc avatar
UTC

Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
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Location: Pleasant Hill, CA
 
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@jimc avatar
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: UTC
Posts: 43923
Location: Pleasant Hill, CA
UTC quote
That sounds just like an EvapCrap issue. Fuel has got into the vent pipe and blocked the EvapCrap's innards.

I strongly suggest you remove the EvapCrap. You can leave the carb connection open, and extend the vent pipe from the tank filler neck down to the outside world on the RHS.
@dooglas avatar
UTC

Veni, Vidi, Posti
GTS 300ABS, Buddy 125, Buddy Kick 125
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Location: Oregon City, OR
 
Veni, Vidi, Posti
@dooglas avatar
GTS 300ABS, Buddy 125, Buddy Kick 125
Joined: UTC
Posts: 13411
Location: Oregon City, OR
UTC quote
This doesn't sound quite right. Even if you had a tank venting issue, I wouldn't expect substantial difficulty in removing the gas cap. The cap is threaded after all (the mechanical advantage of a screw thread). An audible air sucking sound when you remove the cap would likely be noticable as well as an immediate change in how the engine runs.
@stickyfrog avatar
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Moderatus Rana
MP3 250 and 2 MP3 500s
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Location: Nashville, Indiana
 
Moderatus Rana
@stickyfrog avatar
MP3 250 and 2 MP3 500s
Joined: UTC
Posts: 22659
Location: Nashville, Indiana
UTC quote
With Jim on this. Get rid of all of the evap crap. Then if there is still an issue you've at least ruled out a truly worthless appendage.
@greasy125 avatar
UTC

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
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Location: The state of insanity, SoCal
 
Sergeant at Arms
@greasy125 avatar
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: UTC
Posts: 14966
Location: The state of insanity, SoCal
UTC quote
drill a 1/8" hole in the gas cap right in the "O" where it says gasoline.

also, pull the evap line off the carb and you should be gold, pony boy

if problems persist it's time to dig deeper.
@jimc avatar
UTC

Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
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Location: Pleasant Hill, CA
 
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@jimc avatar
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: UTC
Posts: 43923
Location: Pleasant Hill, CA
UTC quote
greasy125 wrote:
drill a 1/8" hole in the gas cap right in the "O" where it says gasoline.
I'd advise NOT drilling a hole there. Not a problem perhaps in the USA, where vehicle inspections are almost non-existent, but elsewhere that could get your vehicle taken off the road and potentially a fine. Even missing the rubber seal from inside the cap is an MOT failure in the UK, where they aren't as strict as some other countries. So "for those listeners elsewhere" please ignore Greasy this one time.
Quote:
also, pull the evap line off the carb and you should be gold, pony boy

if problems persist it's time to dig deeper.
This is so very easy to do, and should help.
@greasy125 avatar
UTC

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: UTC
Posts: 14966
Location: The state of insanity, SoCal
 
Sergeant at Arms
@greasy125 avatar
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: UTC
Posts: 14966
Location: The state of insanity, SoCal
UTC quote
jimc wrote:
I'd advise NOT drilling a hole there. Not a problem perhaps in the USA, where vehicle inspections are almost non-existent, but elsewhere that could get your vehicle taken off the road and potentially a fine. Even missing the rubber seal from inside the cap is an MOT failure in the UK, where they aren't as strict as some other countries. So "for those listeners elsewhere" please ignore Greasy this one time.

This is so very easy to do, and should help.
holy crap, didn't even occur to me and didn't realize that restrictions were that tight elsewhere! thanks for that tidbit jim!

fwiw, this was common practice at several dealers (I'm in CA) and a tactic commonly used for such a problem.

anyway, you could just pull the evap at the carb and the one off the filler neck and achieve the same thing without implementing a drill bit.
OP
UTC

Hooked
2020 Piaggio Liberty S 150, 2016 Vespa GTV300ie, 2009 Yamaha C3
Joined: UTC
Posts: 161
Location: USA
 
Hooked
2020 Piaggio Liberty S 150, 2016 Vespa GTV300ie, 2009 Yamaha C3
Joined: UTC
Posts: 161
Location: USA
UTC quote
So I would not know what a carburetor looked like if it reached up and smacked me in the face, lol. How would one go about accessing this thing, and does anyone know of any good photos/diagrams I could go by?
@stickyfrog avatar
UTC

Moderatus Rana
MP3 250 and 2 MP3 500s
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Posts: 22659
Location: Nashville, Indiana
 
Moderatus Rana
@stickyfrog avatar
MP3 250 and 2 MP3 500s
Joined: UTC
Posts: 22659
Location: Nashville, Indiana
UTC quote
cnvh wrote:
So I would not know what a carburetor looked like if it reached up and smacked me in the face, lol. How would one go about accessing this thing, and does anyone know of any good photos/diagrams I could go by?
Do a search in the wiki section for evap crap. Should turn up what you need to know.
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