Modern Vespa

Making progress, got it running.
1985 px150e
When I got it was running but pouring gas from the carb. Just rebuilt the carb. New float, needle and gaskets.
Turned on the petcock, it starts, but then dies. I was able to ride it a bit, but as soon as I stop throttle it dies. Got the choke open. Confirmed the choke and throttle cables are hooked up correctly. What next? Feels like it's sucking for gas.
FYI I'm novice. First Vespa.

Ok. Got home and a bit more time to play.
I confirmed that I'm getting fuel into the main supply.
When I pull the throttle I do NOT see gas spraying into the engine opening!
I opened the float and needle area, inspected, removed and replaced. New float and needle. I have the previous float sitting around. I removed the main jet, it looks clean and open holes.

Lastly, gonna sleep on it…..
When I cleaned the float bowl there was some debris in the bottom of the bowl. I sprayed with carb cleaner and used a Q-tip to clean.
I do not understand the directional for fuel flow…. But is it possible the float fuel drain to the jet area is clogged? Just trying to think if the gas is not getting past the bowl? Sorry I'm such a novice….

In the bottom of the float bowl is a hole which is the feed to the main jet. It can very well be clogged indeed as you suggest.

You can find more on it searching for increasing fuel flow. There are several very clear explanations with illustrations how to drill the channel larger.
You do the ´same´ with a steel wire.

Hoping for some charitable experienced feedback from MV.
I've reached an impass and need guidance.
I pulled apart the carb again and carb clean sprayed everything. The drainage port from the bowl is wide open and shoots through.
Maybe starting at the basics…. If my petcock is open and I pull the throttle I should see gas spraying into the engine opening? Because I'm not.
I'm using the electric start. Initially it was starting, with full throttle barely maintaining rpm, then stalling. Now I can't start it…… seems starved for gas?

Have you made sure that you have good fuel flow from the tank? A kinked fuel line will cause just this.

Thanks steely.
Appreciate your input.
Prior to carb rebuild it was overflowing fuel.
I've disconnected the fuel line and when I open the petcock gas pours out. I was thinking something like a vacuum lock/air bubble. I opened the gas filler as well.
I just started it, sounds amazing for about 30 seconds. I turn the throttle and some gas sprays into the motor. Then it dies and I can't start it again….
I'm frustrated, but so motivated and excited to get this thing running!
A couple more photos in case I'm missing something….
Only other thing I've done to it was an oil change. Used motul.

Did you pressure test it? A massive air leak does what you're describing.

I feel for you lol, we've all been there. You KNOW it can run but there's something that won't let it keep going!

It does sound like a fuel problem, not enough or too much. I'd pull the plug here to see if it's wet or dry. If it's dry, crack the banjo bolt and see if gas seeps out at the gasket as it should. If plug's wet blow it dry and kick motor over a dozen times w/ throttle open & tap closed to dry out flooded crankcase, then try again.

Sorry for being newby ignorant….. I talked with steely dan and we're wondering if the petcock position isn't open based on my lack of knowledge of this Vespa.
That being said…. It ran fine before my carb rebuild….. so may be my mistake.

Are you suggesting a possible air leak in the carb? Or fuel line?

Also, I'm gonna get a gas can and bring home a gallon of fuel. Maybe the gauge is not accurate and I'm actually lower than I think?

How does the gas tank look inside? I had a similar problem that turned out to be clogged filter screen on the fuel tap inside the tank. It let thru enough to start it easily and run nicely for a short while then would die. I found it first by checking for flow from the tank to the carb like this:

Fantastic idea!
I'm en route to Home Depot now to pick up a gas can. Any chance you know the size of the gas tubing and I can pick up tubing and connector.
5/16 in?

and you won't, because there's not an accelerator pump.

sounds like you've got a massive air leak, bad seal or the jets are clogged up.

also, if you've pulled the tank make sure that the fuel line is 24~26" and isn't kinked.

Omg! Thank you all!!!!
Do you remember your 'first time'????
I appreciate all the teaching, helps me to understand and gain confidence.
After Home Depot run…… inspected the tank, saw the fuel filter, looks clean …. But I noticed the fuel level is at the top of the filter…. Ah-ha moment……. Maybe my 'tank' is dry and my 'reserve level is full…. So I added a gallon of gas…… BAM 💥!!!!!!
I just spent the last 20 minutes riding around my neighborhood! What a thrill!!!!
Next item will be to understand my petcock. If down is open, then is 90 degrees OFF and up may be reserve…

All this hand holding ain't free ya know...
We expect some pics of your scoot now!

Proudly!
Introducing the newest 'not so modern' member of the team.
Exactly what I wanted…. A running project that isn't perfect. Gives me the opportunity to learn and enjoy.

Undo RED lid & clean crap out of the filter.
Remove GREEN & clean the idle jet... when it's clean, hold it up to the sun & lipook thru it to check.
Remove YELLOW & clean main jet.