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@emilym100 avatar
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I've sold my et4 to my step dad and he is hoping to get him running to use for work commuting.

These are the problems:
+ Was working perfectly, topped up petrol, cut out on the way to work.
+ Starts and idles fine but cuts out when accelerate

What we've done/tried:
+ Drained old fuel including taking off the fuel tap
+ Refilled with new fuel
+ Cleaned out the carb float bowl and jets
+ New air filter
+ New battery

After taking off the fuel tap today and cleaning it out entirely again we can get it running at 10mph but If we try to get it any faster it just cuts out.

Any ideas what is wrong? What else can we try/check?
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1980 Vespa P200e (sold), 2002 Vespa ET4 (sold), 1949 Harley-Davidson FL
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@caschnd1 avatar
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Have you changed the sparkplug recently? Perhaps the plug wire did not get replaced tightly. I suggest making sure the wire is securely attached at the spark plug end.

-Craig
@judy avatar
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Did you take the carb totally apart to clean it? If so remember the rubber diaphragm thingie ( i don't know it's true name Nerd emoticon )? If that's not seated properly you won't get over 10-20mph. Go back and reseat it and see if that helps. When we took mine apart to clean it we didn't seat it properly. I got to the road and pulled back on the throttle and nada. We then went back in and found that we didn't seat it right. Hope this helps and good luck
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Classic insufficient fuel symtoms by the sounds of it.

I'd start at the fuel tap first Emily. Makes sure it s passing a good amount of fuel.
@caschnd1 avatar
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1980 Vespa P200e (sold), 2002 Vespa ET4 (sold), 1949 Harley-Davidson FL
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@caschnd1 avatar
1980 Vespa P200e (sold), 2002 Vespa ET4 (sold), 1949 Harley-Davidson FL
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judy wrote:
Did you take the carb totally apart to clean it? If so remember the rubber diaphragm thingie ( i don't know it's true name Nerd emoticon )? If that's not seated properly you won't get over 10-20mph. Go back and reseat it and see if that helps. When we took mine apart to clean it we didn't seat it properly. I got to the road and pulled back on the throttle and nada. We then went back in and found that we didn't seat it right. Hope this helps and good luck
^^^ good suggestion. If you had the top off the carb it's easy to get the diaphragm rubber misaligned.

-Craig
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I just went through the same thing. I could not get the diaphragm seated properly. Finally used a very small amount of Yamabond in the groove where the diaphragm seats. Put some small weights all around the diaphragm and let it set for a couple hours. Worked great. Not sure but RTV may work too.
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UTC quote
Check the carburetor as suggested by other members here.
In addition, check the air-filter, check the wire from the HT-coil to the sparkplug-cap (I just had to change mine on a 2003 ET-125, the old wire was green from corrosion and had snapped...)
One more thing: If there is a problem With the CDI/immobilizer-system, I believe the symptoms may be a bit as described: the bike will start and idle but not accellerate. Is it possible that corrosion or similar may have caused the CDI to short-curcuit With the consequence that the immobilizer need to be reprogrammed/reset With the red/brown ignition key.

I hope Things work out. Why on Earth did you just not keep that fantastic ET for yourself, by the way?
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Hi Emily
I would agree with Capitano sounds like a classic fueling problem. Just had something similar with my 1996 125 ET4. The fuel tap would not let enough if any fuel through, subsequently it would not run. I fitted a new tap and its as right as rain now, starts better and run smoother. I got my tap from Beedspeed in Grimsby, their not expensive about £9.00 + postage just a bit of fiddle to get the old one out.
Good luck. 8)
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UPDATE:

Turns out I installed a pre-leader air filter so swapped it for a new one that fits correctly.

Installed a new spark plug.

Installed a new fuel tap.

Still nothing. Guess It's taking apart the carb again!
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How's the GTS Emily?
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Before you do check the vacuum hose. the one on mine was originally pitiful in material and length.

Replacing that with some new petrol hose from WEmoto sorted a few issues out including a stubborn refusal to start at one time.
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GTS is amazing! Love riding it


The bike starts and idles but won't bloody move! Could this be the hose?
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UTC quote
Opened up the carb float bowl and it was full of gunk, AGAIN!

It is almost like crystalised sugar. This seems to be here everytime we take it apart :/
@le_fameux_knut avatar
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Well, it seems obvious that you need to empty and clean the petrol tank, fuel tap,fuel hose and carburetor manifold thoroughly (i.e. all things that lead to the carburetor), as well as re-cleaning the carburetor.
It should work then. It might be a good idea to get into the habit of adding fuel-additives like carburetor-cleaner with the petrol when you fuel up. This should avoid the petrol to become "sticky", which seems to happen if petrol turns old in the tank.

How is the neew scoot, by the way?

Best regards from Norway.
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Did they pry the seat and get access to the fuel filler last time it was nicked?

Just fearful from your description that they've sugared the petrol tank.
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le_fameux_Knut wrote:
Well, it seems obvious that you need to empty and clean the petrol tank, fuel tap,fuel hose and carburetor manifold thoroughly (i.e. all things that lead to the carburetor), as well as re-cleaning the carburetor.
It should work then. It might be a good idea to get into the habit of adding fuel-additives like carburetor-cleaner with the petrol when you fuel up. This should avoid the petrol to become "sticky", which seems to happen if petrol turns old in the tank.

How is the neew scoot, by the way?

Best regards from Norway.
Yeah, gonna drain it all again and basically start from the fuel tank and work inwards, scrubbing as we go. My new scoot is amazing, handles so much better than the ET4 ever did!
Capitano wrote:
Did they pry the seat and get access to the fuel filler last time it was nicked?

Just fearful from your description that they've sugared the petrol tank.
Yes, they snapped the seat lock to get at everything that was in my bucket, so had full access to the petrol cap/tank , didn't think about them putting anything into it. The bike ran fine for a few weeks after being taken then the problems started and now it's un-usable!
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Thinking about it logically it wouldn't have got past the fuel filter as it stays crystalline in petrol. The cleaning regime you outlined sounds like the best plan.
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Is there and easy way to remove the fuel tank? May be easier to clean with it out of the bike!

Also, out of curiosity, could the fuel tap have been installed wrong? Can the clamps be put in wrong or something? Just read a post on here about it and a guy just tweaked the positioning and his bike ran perfectly!
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@emilym100 avatar
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UPDATE:

Scrubbed the fuel tank until it was squeeky clean. Then swished some petrol through and drained a few times to re-line it before we topped him up and tried to get him running.

Cleaned the fuel line and re-cleaned the carb and jets.

Nothing. Caput. Will start, idle, accelerate then die. Think we have reached the end of our tether , time to visit the vespa garage!
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UTC quote
Before you hand it in to the garage, try to read the owner's manual (if you have not got the ET4 one, then I guess the one accompanying your new GTS125 will do) concerning red/blue keys and resetting the CDI/immobilizer.
As your scoot was broken into, this might have triggered the immobilizer (the idiots maybe tried to steal it fiddling with electric wires without getting it to start leading to it malfunctioning/immobilizing now).

I believe this is what the immobilizer will do...allow you to start it and idle, but it cuts off at 1500 rpm so that you cannot drive it.

Worth a try....

Good luck!
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The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
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UTC quote
It doesn't sound like an immobiliser problem to me - more like a gummed up accelerator pump. It could also be a poorly seated diaphragm, but I'm assuming that's been checked. If it hadn't been working perfectly beforehand I'd have been saying 'check the valve clearances' - however now everything else has apparently been checked (accelerator pump?) perhaps it's time to check those valves...
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UTC quote
Almost sounds like the electric choke is not working, so the bike bogs and dies when you give it gas.
I know you don't want to do it again, but open up the carb and stick a guitar string through the idle jet and the main. The idle jet may be partially clogged from whatever was in your gas.
Put the carb back on, back the air fuel screw out about two turns, and try running it off a gravity bottle of fresh gas, see if it will take gas.
If it's the choke, you can put it on the center stand, and use a can of ether and a deft hand on the throttle to see if you can get it to take gas. This is a two person operation, and you want to get it up to operating temperature and see if it will take gas once it's warm., because it's probably pretty cold right now. If you get it to stay running once it's gotten warmed up, that would point toward the electric choke.
Another trick you can try is to use someone's thumb to partially block the intake for the air box, start the bike and see if it will accept gas and rev up.
Everybody has a different definition of cleaning the carburetor, and based on whatever it is you found in the bowl, you may need to take it completely apart and soak it overnight in a carb cleaning solution. Yamaha makes a great one, but I'm not sure if they sell it in the UK.
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It starts and idles fine, first time.

I then put it on the centre stand and accelerate. I'm able to turn the throttle a decent way and it revs quite well then it splutters and stalls. It's so hard to describe haha. May be easier to video it?

I'd love to fix it myself and not go to the garage. I don't want to be defeated!
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cfmoto glory, piaggio fly50,fly150
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Don't give up you got this when you take the carb off this time do not drain the bowl but look into the carb on the incoming side bottom right side depress the accel pump and watch to see if fuel come up If it does not then pump passage is blocked or pump diaphragm is damaged check in while you have carb off and we can get you through this. Nerd emoticon
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Where are you at with this today?
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@emilym100 avatar
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@emilym100 avatar
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UTC quote
Not had chance to work on Serg due to the awful weather!

Stupid rain! Hopefully when it clears up I can have another go!
@mjrally avatar
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@mjrally avatar
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UTC quote
Start watching aroud the 1:10 mark.

What do you guys think about immobiliser problems?

Do you have the brown key?
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@emilym100 avatar
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@emilym100 avatar
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MJRally wrote:
Start watching aroud the 1:10 mark.

What do you guys think about immobiliser problems?

Do you have the brown key?
I've tried both blue and red/brown keys. Still getting the problems
OP
@emilym100 avatar
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@emilym100 avatar
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UTC quote
I think the problem is too MUCH fuel! I bent/squeezed the fuel line and it rev-ed really high and didn't cut out!

Sold Sergio to a friend of mine who has always wanted a Vespa so I want help him getting going!
@mjrally avatar
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@mjrally avatar
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UTC quote
Pull your carb out and give it a good cleaning and check the float and needle.

Take pics before you start and everyone on here will chime in if you need help with reassembly.

You got this!
@one_dread avatar
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Sounds like the fuel line, had exactly the same problem with mine, I used a bit to much hose and broke the flow of gravity so when as speed i starved the carb which cut the engine to cut out (not something you want to be doing on the A3) Also while your at it replace the spring clips with proper 8mm jubilee clips and replace the vacuum line to the fuel tap.
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