Modern Vespa

I never knew that I just started the bike with out giving it throttle and every time it starts now but dies before it would only crank over and not start now it's actually starting every try but dies down slowly

Pump runs and the engine gets enough fuel to foul the plug.

Maybe check the injector is clean and spraying a uniform pattern (hang it in a glass jar to catch spray), or that fuel rail pressure is good (~35psi). Could also be a failed fuel pressure regulator in the pump assembly.

I'm sending an image now of the fuel pump and the injector working and yeah i had cleaned the engine once I took it apart I was in there so was like why not when I'll get it running it' it'll feel brand new again

Unlikely but ...

Have you checked that the exhaust isn't blocked? Maybe some wasps made a nest in there?

Also curious, have you reassembled yet or are you waiting for an idea of what to check?

yeah I reassemble the whole engine when trying to start I notice the check engine light stays on

And did you try with the lambda sensor disconnected?

I'm sorry I'm not sure which sensor is that where is it located exactly?

Screwed into the exhaust header near the head. About the size and shape of a finger sticking out at 90°


Edit: don't unscrew it, just disconnect the plug half way up the cable.

Oh yes I know exactly which sensor you're talking about I just googled it and no I haven't tried to start it with it disconnected I should disconnect it and try giving it a shot

My '06 (granted an older GTS) would die at idle but would start easily and run - but die once idling. Replaced the fuel pump, no change. Turns out the battery was the problem. Replaced that and voila, reliable start/run. Maybe check / replace your battery. My $0.02

Are you sure you got the timing right when you reassembled the engine?

Yeah I even took images of the timing marks before re assembling

And this is the other photo literally TDC then I also adjusted the valves after 10 for the intake and 15 for exhaust

And this is the other photo of the valves being adjusted

Have you cleaned the idle bypass in the throttle body? That may need cleaning too...

https://cheekythoma3.wixsite.com/itsme/idle

Does it matter on these whether TDC is the compression or exhaust stroke?

It's the same place either way.

My cousin ran into a similar issue. The bike would not start at all, new sparkplug, new Fuel injector. Just would turn over and over again.

How we solved it:
Remove the fuel injector.
Keep it plugged in
Put a towel over the intake hole
Put the fuel injector in a cup
Attempt to start the bike.

The remaining fuel in the cylinder will ignite, and the bike will cough for a second or 2.
Now replace the Fuel injector.

Bike should start with no problem.
let me know when you have attempted this. It has been 300 miles and he has not had another issue with the bike.

I'm trying that out right now and I'm also cleaning out the ecu to see if it does it I'm going to try to remove the o2 sensor as well to see if that can be the issue as well after this

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So I just cleaned out the air flow hole and there was so much dirt and a mini rocks reinstalling now

Started then died again this is how the spark plug came out I just bought this before starting up the bike

How old is the fuel in the tank? Has it been sitting there as long as the bike has been idle?
Also double check the spark plug wire cap. Give it a good twist clockwise. make sure it is tight. a loose connection between the cap and wire can cause a less than optimal spark, which could get extinguished when fuel is added to it.

The fuel I flushed out the fuel system last week and added fresh 93 once I started working on the bike that's the first thing I did was change the fuel and spark plug

I still have a check engine light on

Low battery?

on my hpe the check engine light remains on until the engine is running. can't remember for my older gts but probably the same.

but if you want to actually check to see if there is a code causing that light you can do this: DIY Diagnostic tool for injection Vespa's with MIU ECU

If you are getting spark, and you are confident the Spark is strong. Then the only other option is the Fuel injector, as someone has stated, the injector could be partially clogged. You should clean it the way Robot does it in this video. You will be able to test it thoroughly as well.

Did you ever figure out the issue?

No never I dropped it off yesterday at the mechanics had to make an appointment so I waited about a week but hopefully they'll get in contact with me soon and tell me some good news I'll keep you updated

Thanks for the update...
If you lived out here in Seattle you would not be missing any riding weather. It has been raining nearly everyday. When its not raining we have been getting barely above 60 degrees.

Good luck...