OP
UTC

Member
Vespa GT200, Vespa GTS250
Joined: UTC
Posts: 12
Location: Nova Scotia
 
Member
Vespa GT200, Vespa GTS250
Joined: UTC
Posts: 12
Location: Nova Scotia
UTC quote
GTS250 stalls-won't idle, dies when cold

This problem with my GTS250ie just developed recently. It is intermittent and only happens occasionally.

The scoot rides fine. And it always starts. But over the last few weeks, and only occasionally, right after starting from cold, it won't go to idle and needs to be given gas otherwise it will stall. Most of the time this doesn't happen and it starts up fine when starting cold. So, the problem is intermittent and only occasional. But when it does happen, it worries me because it needs to have the accelerator advanced, revved-up otherwise it will stall, even after running 2-3 minutes. I have not ridden it when it behaves like that and I don't want to. I want to solve the problem. I'd be grateful to hear any ideas you have about the cause and the solution.
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Member
Beverly 350 and a whole bunch of Shovelheads.
Joined: UTC
Posts: 21
Location: Zürich
 
Member
Beverly 350 and a whole bunch of Shovelheads.
Joined: UTC
Posts: 21
Location: Zürich
UTC quote
A quick search shows these bikes have some sort of stepper motor activated additional throttle for idle at cold. This might be failing in your case.

https://www.manualslib.com/manual/986099/Vespa-Gts-250-I-E.html?page=166#manual
@wbdvt avatar
UTC

Molto Verboso
'16 Sprint S 150, 2 x '06 GTS 250, '12 GTS 300, '74 Vespa 150 Super
Joined: UTC
Posts: 1512
Location: Vermont
 
Molto Verboso
@wbdvt avatar
'16 Sprint S 150, 2 x '06 GTS 250, '12 GTS 300, '74 Vespa 150 Super
Joined: UTC
Posts: 1512
Location: Vermont
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What year is it? How many miles on it? What was last maintenance done on it?
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Veni, Vidi, Posti
Joined: UTC
Posts: 7050
Location: Tega Cay, SC
 
Veni, Vidi, Posti
Joined: UTC
Posts: 7050
Location: Tega Cay, SC
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You did not mention how many miles are on the scoot. Anyway, the same problem was occurring on a GTS250 with 12K miles I was working on. The stepper motor is involved, but it is an easy fix - 1) remove the throttle body, 2) spray some carb cleaner down the idle bypass hole on the inlet side, 3) check to make sure some is flowing out on the outlet side and clean the the throat on both sides, 4) reinstall, 5) go for a ride. And if you have not taken care of the maintenance on the air filter, do that as well. Now.
OP
UTC

Member
Vespa GT200, Vespa GTS250
Joined: UTC
Posts: 12
Location: Nova Scotia
 
Member
Vespa GT200, Vespa GTS250
Joined: UTC
Posts: 12
Location: Nova Scotia
UTC quote
Thank you Lebowski, Molto Verboso, and Tierney. My GTS 250ie is a 2007 with 7500 kms. I bought it in 2021 with 2000 kms, so have put on 5500 kms in three years. I changed the oil & filter and cleaned the air filter in 2022 and have added 3800 kms since then. I'm readying for a change of all fluids, oil, coolant, brakes, coming right up and also putting on a new belt, rollers, glides. I sometimes ride in some dusty conditions so will change to a new air filter too. The scooter's been great, reliable, and it's still rides very well except when this cold starting/idle problem occurs which is only about one time in ten and only began a few weeks ago. Like it has a bad day occasionally and woke up on the wrong side of the bed. On those rare occasions I happily take my GT200 instead (2008, 10,000 kms) which has always been utterly reliable since I bought it in 2019.

I will try the carb cleaner down the idle bypass and post the results. And clean out the air filter while I'm waiting for a new one. Good idea- thanks!
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UTC

Veni, Vidi, Posti
Joined: UTC
Posts: 7050
Location: Tega Cay, SC
 
Veni, Vidi, Posti
Joined: UTC
Posts: 7050
Location: Tega Cay, SC
UTC quote
Good you for getting in there and getting your hands dirty,, it is the best way to maintain and understand the health of the machine. Cleaning the air filter and the throttle body is an hour or so of easy work. And good mental therapy.
OP
UTC

Member
Vespa GT200, Vespa GTS250
Joined: UTC
Posts: 12
Location: Nova Scotia
 
Member
Vespa GT200, Vespa GTS250
Joined: UTC
Posts: 12
Location: Nova Scotia
UTC quote
Following up with your suggestions, I was preparing to clean the throttle body with carb cleaner and read a warning somewhere against using carb cleaner for the purpose, and using fuel injector cleaner instead. So, I bought some Seafoam Fuel Injector Cleaner (I think it's similar to all the major brands, STP, etc) and started out by simply following the directions using it as a fuel additive. Voila. So far, so good. (I've never used any fuel additives before, but always strictly used high test gasoline). Several days of problem free starting and joyful riding have ensued on my GTS 250ie. I haven't even cleaned the air filter yet, and at this point I'm not sure I'll bother attempting to clean out the throttle body by pouring this cleaner down the idle bypass as suggested. If further starting problems do arise I will post here again. If not, readers can assume the Seafoam Fuel Injector Cleaner worked by simply following the directions using it as a fuel additive.
@wbdvt avatar
UTC

Molto Verboso
'16 Sprint S 150, 2 x '06 GTS 250, '12 GTS 300, '74 Vespa 150 Super
Joined: UTC
Posts: 1512
Location: Vermont
 
Molto Verboso
@wbdvt avatar
'16 Sprint S 150, 2 x '06 GTS 250, '12 GTS 300, '74 Vespa 150 Super
Joined: UTC
Posts: 1512
Location: Vermont
UTC quote
You may want to purchase a fuel injector to have as a spare. They are relatively inexpensive.
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