OP
UTC

Hooked
Vespa GTS 300 super, Moto Guzzi Griso
Joined: UTC
Posts: 416
Location: Detroit
 
Hooked
Vespa GTS 300 super, Moto Guzzi Griso
Joined: UTC
Posts: 416
Location: Detroit
UTC quote
This has been a bit of a problem since owning it since 2010 and after 20000 miles. Today it would not start after sitting. It cranked for a while the first time than started. After the second stop it cranked ch ch ch noise but didn't start for maybe 15 minutes. On the way home stuck in trafffic it died and didn't start. I pushed it a few blocks to a side street and it started another a few cranks. Let it cool for a half hour and it started right up. Fuel pump noise was nice and loud on key turning. 2 year old battery, changed the starter thing in the front a few years ago, replaced the spark cap and lead, put in a new starter relay this year, one year old coolant. From what I read I would have cold start issues if it wa valves? Will take a look at spark plug in the morning
UTC

Ossessionato
2016 Vespa GTS300ie abs/asr/ess Settantesimo '70'
Joined: UTC
Posts: 3766
Location: East Anglia, UK
 
Ossessionato
2016 Vespa GTS300ie abs/asr/ess Settantesimo '70'
Joined: UTC
Posts: 3766
Location: East Anglia, UK
UTC quote
Have the valves ever been checked? This could be a valve adjustment problem. They should be checked every 12,400 miles. If valves are too tight, the clearances reduce to nothing when the motor is hot. This causes the engine to stall/cut out. You may notice some slightly rough running just before the motor cuts out but not always if you are riding rather than idling. It usually won't start until the motor has cooled. The issue can cause permanent damage to the engine so it's vital to find out if it's a valve issue before you continue to ride it.

You won't necessarily have cold start issues if the valves are tight. It depends which valves are tight and just how tight they are and if any damage to the engine cylinder head has occurred.

You mention you've had this issue since you had the bike, why wasn't this addressed under warranty? and yes, I've seen some bikes delivered with too tighter valve clearances that caused running problems so valve issues mustn't be ruled out.
OP
UTC

Hooked
Vespa GTS 300 super, Moto Guzzi Griso
Joined: UTC
Posts: 416
Location: Detroit
 
Hooked
Vespa GTS 300 super, Moto Guzzi Griso
Joined: UTC
Posts: 416
Location: Detroit
UTC quote
I do need to check the valves.
The dealer I bought it from shut down, recession was hard on Detroit area.
The problem is very sporadic. 1st time I found a wire harness with melted insulation due to resting on a hot engine part. Fixed that no more problems that year. Next time I find the spark plug cap fell apart. Replaced that no more problems. Up front switch, no more problems that year. Next year new battery. Last year, super low on coolant, fixed no more problems.
Today it ran like a champ in Chicago traffic, it was rainy and cool though. At the Chicago scooter rally ride I ran hot in stop and go for 2 hrs no problem. Yesterday problem shows up, a little different than before. Hot day but really not terrible stop and go.
I was wrong about the battery 5 years old, bought a new one, can't hurt
@mayorofnow avatar
UTC

Molto Verboso
2020 GTS 300 HPE
Joined: UTC
Posts: 1350
Location: 🤷‍♂️
 
Molto Verboso
@mayorofnow avatar
2020 GTS 300 HPE
Joined: UTC
Posts: 1350
Location: 🤷‍♂️
UTC quote
I wonder if I'm experiencing the same problem you are, but with 19800 less miles.
UTC

Ossessionato
2016 Vespa GTS300ie abs/asr/ess Settantesimo '70'
Joined: UTC
Posts: 3766
Location: East Anglia, UK
 
Ossessionato
2016 Vespa GTS300ie abs/asr/ess Settantesimo '70'
Joined: UTC
Posts: 3766
Location: East Anglia, UK
UTC quote
Ok so it's clear your starting issues from when you first got the bike are all different, and this new starting issue is presumably being caused by another issue.

In this position I'd normally say scan the bike with PADS (Piaggios own diagnostic scanning tool) to see if you have ECU error codes stored. This will normally tell you what the issue is or lead you to the right conclusion as to what the issue is. If you have a dealer close by then this is the best option if you don't know much about bikes.

In the meantime, I'd certainly check the valves, it would do no harm. Since your description of the issue is now more complete it may not be a valve problem, but I'd do it anyway as its so simple even for a novice. Adjustment needs care and a careful read up first but just checking is easy.

I take it you have checked your battery terminals. If you have a loose one, it will give sporadic symptons as you describe and is quite common on the GTS bikes. There are lots of other causes of your issue, but it may also be that you bike just needs an ECU software update. These are available from your dealer and takes only minutes to do. Piaggio brings out quite a few ECU updates and several of these have been aimed at curing the very thing your bike is suffering from. Again, a quick scan at your dealer will tell them if you bike needs these updates.
OP
UTC

Hooked
Vespa GTS 300 super, Moto Guzzi Griso
Joined: UTC
Posts: 416
Location: Detroit
 
Hooked
Vespa GTS 300 super, Moto Guzzi Griso
Joined: UTC
Posts: 416
Location: Detroit
UTC quote
I should have checked the valves when I did the belt. Looks like Im due for a new spark plug too. Now I live in Chicago where there is a dealer. I'll look and see if they can reflash my ecu.
Mayor I saw your thread. Might be similar but mine is a bit older model. Do check the spark plug wire both ends. Another year year I had similar problem but there was a ping noise before I couldnt start it. Other thread suggested it wasn't the battery but since you have two scoots try swapping the batteries to see if you still have the problem
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