Modern Vespa

Hi I'm Shawn..I have a piaggio lx 150...I resurrected from a barn ...main issue was replacing cdi w immobilizer bypass then juat basic clean out and tune up to bring it back to life ...and ever since it has ran great ,...perfect even...till coming back from store yesterday and very quietly no bangs or pops just shuts off still had power just dies and now won't start ...will crank over and over but nothing more 😔🥺😬...its getting fire , it's getting fuel ,air ??!!?
So what's left , meh ....I'm going to check the valves and beyond that minus possibly another cdi? ...I have no clue what it could be ....please help a girl out 😁

I'm not familiar with these models but if it's got a fuel pump rather than a carb then a faulty fuel pump would be my prime suspect.

Can you check if you can hear the fuel pump prime when you next turn the ignition on.

Hi and welcome btw.

LX150 for '06-'07 was carb with gravity feed fuel. LX150 for '08-'09 was still carb, but with an electric pump to feed the carb. Pretty sure this is one of those two models, since replacing the CDI immobilizer is much easier on these than replacing the MIU throttle body on an LX150ie.

How many miles are on the scoot? Valves make sense if it's hard to start or stalls when coming down to idle.

It would be hard to blame the CDI if you have confirmed you have spark. Fuel starvation makes more sense. Have you confirmed that the fuel tap still feeds fuel when suction is applied to the vacuum hose?

Compression might be a good thing to check too. You can rent testers from auto parts stores. Fuel and spark only work if you can compress the fuel-air mixture to more than 90psi. Disconnect the vacuum line to the tap and turn it over with the throttle wide open. Crank until the needle stops moving. Anything less than 90psi suggests you're in for some top end work.

how do you know its getting fire?

did you pull the plug and verify blue spark?

if so the CDI is doing its job.

Check that all the lines to the carb are properly connected and in good shape with no cracking. This could cause issues with non-running/fuel starvation.

Also confirm that the spark plug lead is firmly attached to the plug. These will wear over time and disconnect due to vibration while riding.

Also - you mentioned this bike was not ridden in a while, you should consider changing the belt and tires - the rubber degrades over time and could be another point of failure and frustration.

Take deep breaths...you're on the right path.

Thanx for your replies ...ok so , spark ,yea pulled the wire w plug and sparked it on the frame , cdi , yes new ...it's a immobilizer bypass..I'm not sure ye year actually but the fuel line goes from tank to filter to carb ...I hit air filter and spark plug hole w starting fluid quickly after putting back in after I checked it ..also got new plug the old one was sparking but it looked all carbon smoked like the apocalypse though still sparking I got new one ...still nada....compression is awesome ..I didn't check it w a gauge or whatever but it pops my finger off the hole when I turn it over ....it sat along time in that barn I'm sure but I've had it up and going for about 6 months now and its ran perfect ....I literally just quit and stopped running in like the blink of an eye ...I was coming from storeI had a bag of ice on the floorboard and my coil is exposed there cause I don't have that cover fairing that goes over the valve cover thing so initially I thought I shorted the coil so that was the first thing I changed ....when it quit it was like someone just flipped a switch no noise just flipped it off and rolled to a stop ....I had been having a bad oil leak the week prior , my valve cover gasket was bad I had changed that and it stopped the leak for the most part but there was before and still a little oil coming out of breather hose that goes from my valve cover and there's a breather hose from the case to the floor board it had oil in it and a bunch of misc weird crap stuck in hose before I changed the valve cover gasket ...it seemed to still be leaking ghere a little ...so I have to remove the rear axle nut that goes trough clutch to get that case off?? I wondered about the rear oil seal at te clutch but was admittingly stoned when i tried to take the case cover off so I spaced on it a bit ...I feel like I took that off when I first got it but don't recall for sure ....a belt breaking would make sense w how it quit but I didn't hear it snap or banging around in there ....also would it still crank over w out the belt but just not move? Today if stupid rain will ever stop Id like to check the belt deal and if it's ok crack the valves back open adjust those of needed ....I didn't have time or cash last week to order a gasket so I used a half of an electric cord wire and some gasket maker goo to make a gasket.. worked well and was riding it for several days before I had this little stroke or fit or whatever....it's my main transportation to work n stuff I drive it 15mi each way everyday and love it minus the recent rain ....I can order some parts now jus wanna make sure I'm ordering the right thing off the bat .....u guys are awesome Thanx for ur help

I ran out of breath trying to read that...

I was going to suggest checking the valves, but it seems like you'll be doing that.

I'd be checking the carb, to ensure it's not over or under fuelling. Also check the rubber intake manifold between the carb and the head - they are very prone to cracking and leaking.

well he was stoned when working on the scooter and probably continued when writing this.

At least it reads that way to me IMO.

This.

The vacuum line from intake boot to fuel petcock is critical, no vacuum, no fuel.

Ok so found it !! It's the upper rocker arm it's just freeing popping around it's not attached properly or something ..there's no tension on it at all to adjust or anything ...however I can't see how to fix it or how it came undone ...what holds it on there ?? Or did it come undone and flip out of place ?? ..I dunno but here's a pic

Maybe it is my eyes but is the tappet screw end broken off, cannot see it in photo

similar to one below, maybe not correct model

https://www.scooterwest.com/adjuster-screw-for-valve-tappet-vespa-484654.html

A photo of the cam end of the rocker arm would be informative - if that's all there and alive and well then you have a valve stuck open, probably jammed into the piston.

The head has to come off at the very least.

Unless that adjustment screw is broken (I've never seen a broken one) or if it is turned out way too far (not sure what it is supposed to look like on that model) then you have a dropped valve, meaning the valve stem is stuck in the valve guide, and the valve spring is not strong enough to close it. If the LX150 is an interference engine, then there is a good chance the valve has contacted the piston. However, if it turns over, and you don't hear any unusual noises, and if it still has compression, maybe not.

A dropped valve is not uncommon on an engine that has sat for a long time without being moved. Engines need to be moved fairly often. If you have access to a borescope, you can stick it into the spark plug hole and see if the valve is in fact open. You can also check the top of the piston to see if there is any damage. If not, try to push and pull on the valve and see if you can get it to move.

If it is a stuck valve, and if you got lucky and it didn't smash the piston, I would recommend removing the head, inspecting everything, replacing any parts that are damaged or worn, and definitely replacing the valve stem seals.

Did you find the broken piece?

The broken piece ended up being the little nut type thing on the end of the adjustment screw that pears on the valve spring...I replaced it w a nut that fits the adjustment screw till I can get a whole new screw ..have to order it id imagine from where I live ...I had it together but on way to work it came undone again ...I'm waiting on side of road currently for rescue

Did you make it home alright?

I'm having trouble understanding what broke. I don't see an adjuster or locknut missing in your photo.

And if a nut or other piece came off in the head, then I'm really surprised you were able to replace with your own hardware and that it ran again (even briefly)!

So it was the other end of the tappet screw, needs to be changed