Engine dying - what to check?

[fraserp200e]

I've got a standard non-autolube P2 engine which has just died on me a few times in the last couple of weeks. First couple of times (one day last week) last it was just ticking over, waiting in traffic and waiting to turn at a junction and the last twice (this morning) has been when I've been riding along 50-55ish. I use the scooter most days for work and it's been fine the rest of the time.

Engine just dies like it's ran out of fuel. It then won't start again by either kickstarting or bumping it.

Whilst it won't start I've checked;
It's getting a spark (I've also changed the plug)
Compression feels good / normal
Getting fuel at carb float bowl and at the carb down into the crank
Disconected the green wire at CDI, so don't think it's the key switch
Checked for obvious earths / electrical / cabling snags under the horncast and at the CDI/engine junction box but can't see anything obvious

Every time it's happened it's started again and run fine after sitting for a while or after faffing about at the side of road but not finding anything obvious. Normally it starts fine and runs well...........until it dies.

I'm thinking it's something electrical but I'm going to have a proper look later on, anyone got any suggestions for anything I've missed?

[shaunmc]

I had a similar problem on a T5 , a mate wi more knowledge than meself checked the carb and electrics, ended up buying a new carb and it sorted problem. Could you borrow a working carb off a mate and try that first.

[fraserp200e]

I've got another P2 that I can take the carb off, it's just a pain in the ass that it last for days with no snags then dies (normally on the way to work!).

Anyone else had anything similar?

[HxPaul]

If its like a Lambretta it should have a breather hole in the fuel cap,if this is blocked it will cause these symptoms.The quickest way to check is to unfasten the fuel cap and go for a ride,if it doesn't cut out you have found the problem.

[fraserp200e]

Cheers Paul, it is the same but I've not tried that so I'll give it a bash.
There's nothing stored under the seat so the air hole (for the carb) is definately clear too...........

I've just been to collect it from where I left it this morning, started first kick and died again after about 2 miles. (Hope none of my Lambretta riding mates read this )

[HxPaul]

The air hole under your seat that can become blocked by carrying something,such as your waterproofs is a totally different hole,that hole controls the air going to your carb,the hole that I am talking about is a pinhole breather that is actually in the fuel cap.

[bristolmod]

intermittent dry joint on the electrics...........somewhere. The best type of fault!!

Chris

[fraserp200e]

The air hole under your seat that can become blocked by carrying something,such as your waterproofs is a totally different hole,that hole controls the air going to your carb,the hole that I am talking about is a pinhole breather that is actually in the fuel cap.

Yep I know the the hole you're on about, I was just saying that the other (carb) hole is clear. Had a blow through the petrol cap hole and it seems clear enough but I'll give it a bash with it off just to make sure.

[fraserp200e]

intermittent dry joint on the electrics...........somewhere. The best type of fault!!

Chris

It's starting to look like that I think.

I've just had the carb to bits and everything seems fine, a little bit dirty but not too bad. I'll try another carb just to rule that out though.

[holty]

had a similar intermitant problem with a vespa once, turned out the stator wires had rubbed on the casing and was earthing out now and again, taped it up and problem solved, it was only a pin hole but still caused it to die, and when checking the plug it always sparked, i only found it when i went to change the stator, might be worth checking yours, i have intermitant electrical faults, they can be hard to fix, good luck.
holty