Modern Vespa

(Weird, I wrote this already, for got to submit it and when I did, it disappeared. So here we go again. Anyone else notice this?)

Riding home from work tonight, I rode through town, entered the freeway and sped up to the 55 mph limit. In about a mile it goes to 65, and I had it WOT hitting around 70......when it just died. No noise, actually just silence....bike coasted to a stop and wouldn't start. Was going to poke around under the bucket, but it was too hot, but everything looked in order....It turns over just fine, but won't start....

So, called my wife, and at the same time a motorcyclist stopped to check on me....I got distracted and went to talk to the guy, meanwhile my wife just heard road noise and freaked out a bit. Anyway, I was luckily a couple miles from home...she picked me up, I went home to get my trailer and tie downs and back to load up the scooter. Kind of grateful I've had a lot of practice with trailering because it was pretty much second nature and not stressful.....

Now the troubleshooting begins. I can't imagine anything catastrophic or it would have bee noisier...I hope. I know there have been problems with spark plug caps/leads, which would be my starting point, but I'm really not sure how to troubleshoot that.

Any input is welcome!

Reseat plug lead. See if it starts.

Remove plug, check for spark.

I would be suspicious of the fuel pump.

Also, forgetting to submit a post and also forgetting you dialed your wife are both troubling signs.

Not necessarily in that order.

And possibly forgetting to put gas in the scooter?

That too.

Gas was 3 bars when I started it, so good there.

Made good with the missus, though, er, there was a conversation about my priorities...

Too late and too tired tonight to dig into it, but she's safely in the garage. I'll have a look tomorrow.

Maybe check the fuel pump first.... the spark plug and I don't have a very good relationship....mostly due to my big hands...

Are you actually sure you were riding the scooter and not watching a car chase movie on the couch?

That might explain a few things...

I think you’re on to something here.

Bullitt?

Did i misquote you? 😀

... Ah ... the Vespas ... Incorrigible, many of them arrive here in the workshop from the dealer friend ...
Mainly for problems of maintenance not performed.

I'm thinking spark plug wire / cap popped loose.
Same thing happened on my GTS (riding at speed, sudden *nothing*).
But then, it wasn't actually the plug cap's fault....

I had a Genuine Blur ss220i before my BV350. I was riding to work one day and it just flat died like yours. I couldn't figure it out and took it in. They found a burnt CDI controller (It was a sealed block and had burst open). I never would have figured it out. I hope yours is easy.

Thank...or at least easier than that.

Okay, I'm back...haven't been ignoring scooters but my BV was really wanting a new seat cover, and got it. Gotta succeed at something once in a while.

Anyway, back home to the dead GTS. I was wondering, if you still hear the whirring on turning on the ignition, is that enough to show the fuel pump is working? Or do I have to see gas spurting? If so, I should be looking for a fuel line somewhere....

Popped the spark plug cap off, it was intact and pretty snug. Not sure what else to do with it. I'm a little fuzzy on checking spark. I've done the old fashioned way but the new caps seem to be a bit more of a challenge...

Finally, a question on where the spark plug wire actually goes...I've traced it into the bowels of the scooter, but it disappears from sight once it crosses to the left side. Is it possible that there's a problem at the other end?

When you say "whirring" is it the sort of "chugachuga" of a crank rotating, or the "whirring" of a starter spinning but not the crankshaft?

As to the other end of the spark plug wire, yes, it could also become de-attached.

I just turned the key, didn't engage the starter.

Any idea where it goes? Seems kind of mysterious to me and I can't get in there to feel my way around either...

So, maybe time to check for spark? (just found the wiki....) I dread going in there as I'm guaranteed to skin the back of my hand at least once....

It goes to the coil, which (if memory serves, and it frequently doesn’t) is under the floorboards somewhere.

But it’s been so many years since I actually did this kind of stuff, my memory is not to be relied on.

Yes. It doesn't prove that the injector is working though...

Beat me to it, Jim.

Melody's first bona-fide failure came by way of the fuel injector body snapping in two. This was likely the result of a crack developing in the injector body after the bike suffered a very big pothole-dip while riding in Brooklyn just a few months before. And, I went through the same business after it happened: turned key, heard fuel pump do its thing, pressed Start button, engine turned over but didn't start.

Now that you mention it, I had... erm, I mean, my wife had an MP3 250 that suffered the same fate. Electrical connector broke off the injector, but it was a gradual thing. Shut off, started , shut off days later, didn't start . Finally one day I was looking around, wiggling stuff, and the connector along with the part of the injector stuck inside the connector, came away from the injector. I guess that was good news.

My '09 just quit in Prairie du Chien WI, back n 2017. Turned out to be the fuel pump, which was recalled, which i had ignored. After the tech in Cincy replaced the part, it still failed. Turned out the injector was also toast. replaced that and she has been running ever since.

If we have the same engine (the MASTER, as Piaggio called it), the whirring when the key is first turned but the starter isn’t pressed is a couple of things: the fuel pump priming, and the worm drive motor cycling on the idle bypass circuit in the throttle body. On my engine the worm drive sound is more prominent. If those sounds aren’t happening there is something wrong with the power to the fuel system. Dying at speed isn’t likely due to a problem with the worm drive itself, which is good news, because replacing the throttle body is expensive.

The coil is screwed in several places to the frame right below where you put your left foot. You might - MIGHT - be able to follow the spark plug wire back to where it attaches to the coil with your hand without removing all the covering panels to confirm a solid connection.

But I think you have a fuel pump problem. Mine died at speed just like yours and was gushing fuel out of the bottom of the scoot - turned out one of the fuel lines had popped out, leaving the pump to enthusiastically attempt to push fuel everywhere except the injector line. It was an alarming break but an easy fix, once the panels were removed.

From this however I learned that fuel injectors are easy to replace and they are also quite cheap if you look on eBay with the correct Piaggio part number.

There was an old post on the subject ... I don't know if it's useful in that:

DIY Diagnostic tool for injection Vespa's with MIU ECU

I was about to do a deeper dive into sorting out my problem, I pulled out the pet carrier and looked around a bit. What I must have missed yesterday was a crack on/near the fuel injector. ( I'm not too adept with this part of the scooter).

Anyway, I'm hoping this is my problem. Guess getting this sorted is my starting point.

Nora's MP3 250 had the electrical connector break off the fuel injector.
Looks like you have the same situation.
New injector for you!

Careful when you order the new one; they come in "with" or "without" return.
Looks like you need "without", so just one side with fuel connection, other side blocked.

https://www.scooterwest.com/fuel-injector-150cc-300cc-vespa-and-250-300cc-piaggio-8732885.html

Much lower price here though:
https://www.af1racing.com/OEM-Vespa-Fuel-Injector-8732885

Thanks, Robert. Looks like 6-8 weeks from AF1 though. SIP has the same price....higher shipping, for sure, but they've got nice bling.....

Look about right?

https://www.sip-scootershop.com/en/search/8732885

Looks right.
It's the same part number I put in, and about the same price.

Great.

I decided that even though its a tad pricey, it sure beats the gymnastics I do pulling out and replacing the plug for example. Happy to pay the price.

Depending on how much you want to wait around for parts during peak riding season, and spending money, you might want to note that you can have the injector and electrical connection, not the plastic fuel line portion assuming that’s intact, for $16 by Tuesday if you search for “IWP182” on Amazon (Prime).

https://www.amazon.com/EPSIRMP-Injectors-Compatible-Piaggio-PI8732885/dp/B08TTGKJZ2

Umm, that price seems a bit dodgy. Besides, it doesn't seem to be the complete unit, at least to me.

As you wish, but for $16 there isn’t exactly a lot of risk and it looks as though you’d have weeks to test drive the cheap part. If you look at the part in your scoot there’s a plastic component that attaches to the pressurized fuel line, and into that fits the injector with the wiring plug that attaches to the ECU. The combination of the two are what cost >$100, but they are absolutely distinct components.

...and it looks like the plastic component is what faled...

The damaged little grey plastic part you're pointing to is the ECU electrical connector, and is part of the injector. The larger black plastic part is the other of the two components which are part of the expensive Piaggio assembly. That rather simple part is just the junction between the fuel line and the injector. It appears fine, and is held in place by the hex bolt near the left edge of the photo.

The injector part is retained in the black plastic part by that metal clip just above the orange disc in your photo, and is sealed in there with an O-ring. The injector is sealed in the throttle body with friction from another O-ring, and the two parts are held securely in place by the hex bolt.

Remove the hex bolt, tug out the injector, pull off the metal clip, and the injector separates from the black plastic part, which remains attached to the fuel line. Reassemble with new injector, reconnect the electrical plug to the grey socket, retighten the hex bolt - and you're back on the road by Wednesday for $17, assuming that was the problem. (Regardless, the broken grey plastic connector IS a problem.)

These photos of the eBay injector I bought for my 460cc engine might help clarify. Its electrical connector is black instead of grey. I'm guessing this one spritzes out a little more fuel mist than yours - perhaps the electrical connector color is how one distinguishes between the two.

https://www.ebay.com/itm/233187384037

The Piaggio exploded parts diagram for my 460cc makes no distinction between the two components of this injector assembly. This definitely helps obscure the fact that the injectors can be sourced independently of Piaggio.

If you trust the website selling it, at least, you can see that there is a sort of security circlip that holds the fuel delivery line to the top of the injector. Since your electrical connection is the part that is broken you could perhaps just buy the lower metal bits, and install the plastic fuel delivery part on top.

Why doesn't Piaggio supply it in such cheap format you ask? What's in it for them, I ask back....

Caveat emptor and all that carpe diem stuff....

What would I do?? What I did; I bought the one from a well known scooter supply house, at some additional cost.

Well, kind of water over the dsm at this point, but seeing the plastic bit is what's toast, it seemed like I need the assembly to get it. If my injector was toast, the individual part would be perfect. Nicht wahr?

It's the lighter plastic bit that is broken. The black tubes on top appear intact.
I guess put it this way; save your injector for the next time someone has a broken electrical connector, then propitiously post on the freecycle thread....

Okay, epilogue.

Part was waiting for me after my scooting trip. Got to it tonight, not all that hard to figure out disassembly, put the new one together and tried the starter to check for fuel, and yep, spraying fuel! Mounted it and hit the starter again and no start. Then I remembered I'd disconnected the spark plug cap. Got that snapped back with the usual difficulty and it started up....I'd swear better than before.


After a closer inspection, I could see that Juan, you were right on it. I don't really regret taking the expensive route, just for security, I guess, and the uncertainty at the time. Next time maybe not. Anyway, I got a shiny new SIP tee to wear while working on it and a couple of spare mugs, so it wasn't without it's compensations....