Modern Vespa

I have a 2002 ET2 with Weber carb. No special tuning. Original exhaust. It has become difficult to cold start it. Less than 8k miles. It refuses to fire up with no throttle-starter just churns away. It seems like fuel is taking a while to get through to the piston.
If I give it full throttle it was still taking around 20 seconds on the starter button to catch then pick up-starting slow and then ramping up to normal throttle response. Once it is going, it runs/idles great. And restarts immediately.
I have replaced the vacuum fuel tap. Checked the Auto choke extends with 12v across it. Washed and oiled the air filter. On a recommendation I replaced the manifold (the new one from Fowlers had a larger rectangle intake than the original). I cleaned everything in the carburettor. Now it will not start and the plug comes out drenched in fuel.
I would appreciate some suggestions on what may be going wrong!! What to try next!

it actually sounds a bit like your choke isnt working right...its also very possible that your idle jet is clogged...

are you saying that it was tough to start but would start if you gave it lots of gas?...and that one of the things you changed was the manifold and now your plug keeps fouling?

Yes. Before I changed the manifold I could start it from cold by simply giving it full throttle on the starter. At that time I thought it was taking too long to get fuel to piston. When changing the manifold I used carb cleaner on all the jets etc in the carb. On reassembly neither method of starting seems to work and the problem seems to be the opposite-too much fuel swamping the spark plug.

ok well... if you have to give it full throttle to start it...that indicates that the choke isnt working properly.....when bikes are cold, they need more fuel to start...hence the choke...once the bike warms up, the extra fuel from the choke is not needed anymore...

1 - do you still have your original manifold? if its not cracked i suggest putting it back on....

2 - carb clean/rebuild ...perhaps something isnt right...i would take the carb off again and disassemble again...be sure you can see thru the jets if you hold them up to the light.....also be sure the float works properly...

pics would be super helpful

let me know how you make out... i have an et2 and i can help

As Jixaw said if the old intake has no cracks and is sealing correctly put it back on. Are you getting Spark? The plug drenched in fuel could mean that you have no spark.

A degree of embarrassment here.
A few months back I fitted a brand new vacuum fuel tap properly. Months later I heard about starting problems and I have tried just about everything from fule in to carb onwards.
But in between time a Scooter dealer in Bristol stung my son for £120 to try to resolve the starting issue. He may have cleaned the carb and replaced the spark plug but I had not appreciated he had also played with the fuel tap. On closer inspection the larger ID pipe had been put on the lower (small OD) fuell tap pipe and the smaller ID pipe had been put on the large OD upper fuel tap pipe.
A flash of inspiration told me this might be wrong!!! Perfect start after an overnight.
What baffles me is how the fuel tap worked at all with this criminal incompetence. Wish I had started my journey at that point but it was the one thing that I knew was "new".
Is it humanly possible to crank up the rear wheel nut without removing the whole exhaust (have removed split pin)? And if it has to come off what is the best tool for those 10mm nuts that hold the exhaust to the barrel?

Glad you got the issue with the fuel tap sorted. Regarding the exhaust, I'm pretty sure there's not enough clearance to get to the rear wheel nut without removing the exhaust. I managed to remove mine with a wrench by accessing the 10mm nuts through the spark plug access panel (below the front end of the seat), but I recall it being very awkward due to the small space available. It's basically the same as what this guy did: www.youtube.com/watch?v=I8Q6uyF0Z7c

im glad you got that sorted out!

unfortunately you will need to remove the exhaust to get at that wheel...i have tried and theres no other way....its really not too bad to get to but unless you have a lift you are going to have to lay on the ground and get dirty.....10mm and you can access them thru the spark plug access door if needed....its not fun but its doable

ET2 Exhaust- I just had to get down on my side to get those two 10 mm nuts off on the exhaust. I took mine off to get the rear tire off. I brought it to a moped shop where the guy put my new tires on for $40. Not easy for me to reinstall in the heat but managed to do it. I changed my gear oil while the rear tire was off. The tires off my 2002 so at 19 years I was worried about dry rot. Only 175 miles though.

Whoa!

Necro thread warning! I love it!

Yeah, I noticed that today too! I agree it's a very helpful new feature!