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Vespa ET4 125 ('98)
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Vespa ET4 125 ('98)
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For all the electrics wizards:
I recently bought a Vespa ET4 125 and went around on it for a day or two with no probs. It was often hard to start (not first time off the button etc), but I put that down to it's age ('98, 22K).
One morning it wouldn't start and the battery was weak, so I charged it; when re-installing it, I attached the positive wire to the battery, but when the negative wire of the loom touched the negative battery terminal, it started sparking as though I had pushed the ignition button.

I investigated further and noticed that the starter relay looked worse for wear (coming apart, bent terminals). I bought a new one, installed it (made sure the battery was charged) and it started - with no 'battery terminal ignition' problems either.
Then it stopped in the middle of a shopping trip Crying or Very sad emoticon . I wheeled it a few hundred yards and then decided to try it - it started

Rode to work today and the same problem has arisen - spark is weak, charge the battery, touching loom to battery terminals starts the ignition.

Is there something that could be dislodged or fouled in some way that would indicate a particular problem?
Could it be an earth problem?
I don't think it is the battery, fuses or starter relay.

I have bought a new battery just in case which should be arriving soon.

Any help is much appreciated!
Thanks,
G
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Good job finding the bad relay - the relay contacts switch a lot of current and eventually get pitted - or can fuse together, as was so in your case as you describe it.

Your starter motor could very well have a dodgy earth connection. That would be a good thing to check anyway given the symptoms you describe. You might also check the earth connection of the battery's negative cable. Check that the connections are clean and tight.
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Cincinnati John wrote:
Good job finding the bad relay - the relay contacts switch a lot of current and eventually get pitted - or can fuse together, as was so in your case as you describe it.

Your starter motor could very well have a dodgy earth connection. That would be a good thing to check anyway given the symptoms you describe. You might also check the earth connection of the battery's negative cable. Check that the connections are clean and tight.
Thanks for the reply John.

Yea, the starter relay's case looked a bit cracked and when I popped it open, the relay switch (I think that's what it's called) was on connecting the wrong side - so I imagined it was completing a circuit which would only be done by the ignition button being pressed. However, the same problem is happening!

The earth on the negative cable was certainly tight, but not as clean as I would like; I have left the scoot at work and will bring some cleaning gear tomorrow.

How do I get to the starter motor to check the earth connections? It is very possible that contacts are dirty or loose.

Thanks again.
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I believe the starter motor is grounded through it's mounting on the right side of the crankcase, but I don't know this as I'm not intimate with the ET4. There are exploded diagrams in the parts manual, found here:
http://www.wotmeworry.org.uk/manuals/ET4/
Follow the wire from the relay down to the motor. If no separate negative lead is seen, the motor is grounded through its mounting.
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Cincinnati John wrote:
I believe the starter motor is grounded through it's mounting on the right side of the crankcase, but I don't know this as I'm not intimate with the ET4. There are exploded diagrams in the parts manual, found here:
http://www.wotmeworry.org.uk/manuals/ET4/
Follow the wire from the relay down to the motor. If no separate negative lead is seen, the motor is grounded through its mounting.
Thanks again. I'll take a look.
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Vespa ET4 125 ('98)
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Worked on the scoot yesterday.
The earth connections I found were:

1. beside the starter relay
2. below the luggage bucket (shown in photo 2.)
3. below the luggage bucket (shown in photo 2.)

I loosened, cleaned and retightened them all.

There is also a connector/ plug which is disconnected, any ideas what's it's for? Photo 1.

I must say, that it's in a bit of a state, with electrical tape and cable ties all over the place!
It would be good to keep the scoot, but it'll require some serious TLC and more cash! Gah! I thought I could get a bargain.

edit: I cleaned the parts that really needed it and put it back together. The scoot started with it's usual reluctance, and I made it home from where I was working on it.
But this morning, the spark was really weak and the the battery was low after a couple of tries.

I am waiting at home for a battery to be delivered and hopefully it will arrive before I have to leave for work.
for?
for?
earth connections?
earth connections?
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I'd have to delve into the service manual to see if anything there bears resemblance to your photos. Maybe someone who's familiar with the ET4 can chime in. I take it that photo #2 is the "before" picture - those earths look quite loose. Did you see anything down at the starter motor itself? And you say the chassis end of the battery negative wire is tight, yes?
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KTM Super Duke 1290, Vespa GTS 300
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The service manual won't help as this is a pre-leader. I'm quite willing to have a look at it if the owner wants to bring it over at the weekend sometime....



I agree those earth connections are too loose and part of the problem.
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You're a good man, Doug!
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Vespa ET4 125 ('98)
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Thanks for the replies.
Cincinnati John wrote:
I take it that photo #2 is the "before" picture - those earths look quite loose.
Hehe! Yes, the photo of the earth connections was taken 'pre-tightening'!
They were actually very tight before, but I loosened, cleaned them and re-tightened them for good measure.
Quote:
Did you see anything down at the starter motor itself?
TBH, I'm not sure where it is
Quote:
And you say the chassis end of the battery negative wire is tight, yes?
If you mean the connection close to the battery, then yes - clean and tight.
DougL wrote:
The service manual won't help as this is a pre-leader. I'm quite willing to have a look at it if the owner wants to bring it over at the weekend sometime....



I agree those earth connections are too loose and part of the problem.
Wow, that's very good of you Doug. Consider the offer accepted. I will PM you soon; though hopefully the new battery that arrived today will do the trick!
⬆️    About 2 years elapsed    ⬇️
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Piaggio Vespa ET4
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I'm having the exact same problem almost word for word, what solved it on the end?? I really need some help,, Crying or Very sad emoticon
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