Modern Vespa

My wife's 2017 GTV (1040 miles, all stock) has been running fine recently, until this past weekend. It would turn over strongly, but never start. I posted a previous thread asking about a similar experience here...
https://modernvespa.com/forum/post2531689?highlight=#2531689
So this time I checked the boot again but no change. I smelled gas and figured it was acting flooded. Weird for a F.I. motor, I thought. I disconnected the electrical connector on the injector, ran the starter for a few seconds, thinking it might clear it out, then reconnected the injector and it fired right up. Is this some failure that I'm not aware of with this EFI system? This repeated itself several times throughout the day, always starting right up after "clearing" it by disconnecting the injector. It seems that when this was happening the EFI/ARS light would be blinking. Is there a way to scan for codes, or is that not a thing with this system?

Last edited by WaxhawFive on Mon May 09, 2022 7:36 am; edited 1 time in total

Any chance you filled up the tank before beginning your ride? Sounds like an overfilled EVAP system. Is the scooter's EVAP system still in tact?

No, I did fill it later in the day, after we got it running, at least I believe that was the timeline. Everything is stock on this bike, including any emissions stuff. When I filled it the nozzle shut-off didn't work, and I overfilled it, to the point that the fill neck was totally full and gas ran down the back side. What happens if the evap gets overfilled?

Sorry to hear of your issues. The EVAP is the achillies heel for USA scoots. Just type in 'Evap Cannister' into the search feature and you'll get many hours of thought provoking reading.

Geesh, what a deep can of worms. A lot of the symptoms sound like mine. I'll temporarily unhook and plug the canister and rollover valve just to see if there's a noticeable improvement. The no-start happened again yesterday after a brief stop at a store, so engine was hot. It was previously running fine. I also located the diag port connector, so I'm learning as I go.

I wish you well, keep us posted on your progress.

Give these two threads a read. Your canister gets filled with liquid when you overfill. It should be filled with fumes. Now it won't vent. Creates vapor lock for you.
BV250: Evap System Removal

Evap hose at fuel tank disconnected

This one also: I tore out her EVAC System

This weekend it won't start at all. I haven't removed or disconnected any of the evap system yet, just tried to go for a ride with my daughter. I pulled the injector and I'm getting a nice squirt of fuel. I pulled the plug and I'm getting a healthy spark. The battery is fully charged and it turns over quickly. I pulled the air filter and it looks like new with some clear/light gold oil accumulated on the lower corner of the foam. As a diagnosis I did clamp shut the hose coming from the charcoal canister to the intake using locking hose clamp plyers to eliminate the possibility of sucking overflow fuel out of the canister. No change. Any ideas?

It sounds much like a starting problem I had on my 2015 GTS, because the ECU diagnostics buffer was full. I do my own maintenance, and as a result the EU diagnostics do not get checked and cleared regularly. A Vespa dealer workshop should have the electronic equipment to do that job. But if your scooter is regularly serviced by a Vespa technician then that shouldn't be the problem.

I should have mentioned that there is no CEL illuminated. Mike, I've never heard of a full fault buffer that could purposefully cause a no-start condition. Is this for real? I've had to live with, and work around, ODB issues and even performed aftermarket ECU tuning in a past life, but never seen a system that would cause this by design. I'm new to scooters, so I'm just catching up, but this seems strange.

I would also think that if the ECU were purposely preventing the engine from running, it would do so by cutting fuel or by cutting spark, or both, or by simply not engaging the starter at all and setting a code. However, in my case, I have fuel and spark, and no CEL. I also cleaned the injector according to the video by Robot at ScooterWest, using injector cleaner, compressed air and a battery.

Any other ideas?

Have you disconnected the Evap Crap at both ends yet, leaving the tank vent open and the ECU connection closed?

If so, and you still have problems, double-check the injector for being leaky, having a duff spray pattern, or a wonky electrical connection.

Yes, open tank vent and closed port at the intake manifold. Injector has been removed, cleaned and tested, spray pattern looks fine

And it doesn't leak if left under pressure I assume? Last time it was the spark plug lead/cap. Double-check all those parts, as you may have a strong spark with the plug and lead moved away and up for testing, but in its usual position it's intermittent.

It's what I'd go back to to check, if it was me.

I just ordered a new cap and plug. It's so hard to get in that tight space with my hands. Installing the new cap is gonna be tough.

I had a starting problem with my then-new 2017 150 Sprint; at the first service, the only fault found was related to an accumulation of fault codes. With these cleared, the starting issue vanished.

Cadbury, did you have an illuminated check engine light when this was happening?

Don't you guys agree that if the ECU were purposefully preventing the start, it would do so by cutting spark or fuel, or both?

No there were no warning lights illuminated. Just became increasingly hard to start.

DIY Diagnostic tool for injection Vespa's with MIU ECU

interesting.

here's a quote from the GTS 300 workshop manual

And if not cleared over time, that data is overwritten by new data once the buffer is full. That's how it works with automotive ECU's, and I would think the same here. Plus, my EFR/ABS light is not on.

Don't you agree that the presence of spark and fuel spray indicate that the ECU is happy and trying to start the engine?

yeah, saw that comment. thought what I found was interesting anyway. dunno. I ain't not expert but yes I would.

ScooterWest replied to an email with "check the valves and compression". I would love to check the compression but it's impossible to get my compression tester to the spark plug hole. Is this an engine-out task, or is it possible to disconnect the rear suspension and swing the engine down far enough to get to the spark plug hole?

This idea is a long shot, but if you have spark, it has to be at the right time. I don't know how the ECU gets the signal to fire the plug. It may use a crank or cam position sensor. If that sensor is out of position, the ignition timing will be off. Again, a long shot.

True, who knows from where the ECU gets it's crank/cam position signal?

It's not a cam sensor. I believe the crank sensor is part of the stator

I dread writing this, but it's alive and well. Dread, because there was no eureka moment, no smoking gun, no clear root cause of the problem. I was away for a couple days for work so I left the battery disconnected to attempt a ECU reset (probably not even a real thing). Upon returning I installed the new spark plug and boot that had arrived. Tried to crank, no luck. My F-in-L had suggested I try to leave the charcoal canister line OPEN, rather than closed. I tried this and no change, still no start. While frustrated and pondering, I tried several more times, even resorting back to my old trick of disconnecting the injector signal, turning the engine over to "clear" it out, then reconnecting and trying again. After doing this several times and getting no results, while also trying it with the eval hose open and closed, I eventually heard a little sign of life. After a few more tries is started, roughly. Sputtered, shook, then settled into an idle. It didn't immediately respond following any of the changes. It just slowly came back to life. I can't say it was the plug, the boot, the evap line, the ECU "clearing", or anything. I took it for a short ride afterwards and all seemed well. Slept on it, rode it again, then took it on a 40-mile ride, with several stops and starts, and it's now acting normally.
I'm glad, but frustrated to have not determined the cause of the issue, and will be afraid that it could happen again without warning.
I do notice that I see the immobilizer light blink a pattern that matches the D pattern described as...
D= Transponder is not detected.
A single short flash, then two short flashes, then comes back on.
The chip in the key has not been seen.
Either there is a fault with the key or the aerial.
If you have another key try that, if it is still not detected it is probably the aerial.
Verify that the aerial is correctly located and secure in it's mounting around the ignition lock.

except that in my case, after the two short flashed, my light does not remain on, and obviously it starts. This light pattern happens as soon as I turn the key to the ON position with either my blue or brown key, and never repeats until the next time.

Maybe the problem was related to the immobilizer all along, but it's strange that it was always exhibiting symptoms of attempting to start; spark and fuel.

Any thoughts? Thanks for all of the responses so far!

I'm not confident that your source of flash patterns is correct for your 2017 gtv? I traced you quote back to a 2006 pdf. maybe the newer ecu in your scoot has some different patterns? Immobiliser systems patterns (note date inside pdf)

follow up to my previous

try reading from page 81 onwards in https://www.vespaforum.com/manuals/Vespa/GTS300-2015-ABS/GTS300-2015-ABS.pdf

Steel, thank you for that link. I will save it for the future as it's essentially the same as my '17 GTV. Unfortunately there is no blink pattern shown that matches mine, which is a short pulse, followed by two blinks, then the light remains off. It's similar to diagnostic code #2, except my light remains off. I may look into replacing the aerial, as this is what is suggested for this code.

One thing that has happened to me after an engine rebuild. I would get intermittent starts.
I put a new spark plug in
I cleaned the fuel injector

Solution: the Spark plug wire cap came loose. Gave it two or three full twists until it the cap was tight against the wire plugged it back onto the spark plug.

I have not had a problem since. The connection between the wire and the plastic cap acted as a resistor and cause the spark plug to have a weak spark.

Always go the the basics first.

Throttle body/ECU problems, perhaps? Mine wouldn't start intermittently for months. Throttle body/ECU was the issue… If it happens again give it the "throttle body tap" and see if that improves things…

lol

No warning lights on the dash?

And what was your long term solution?

Eventually a young man here in CT replaced the ECU/Throttle body. That fixed it!