Modern Vespa

I bought a used, low mileage 2018 BV350 that worked fine until I got it home.

The symptoms
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It starts up after holding the starter button down for exactly 15 seconds. This only happens after its been sitting over night or for many hours.

(For quite some time, I actually thought it wouldn't start at all. It took some cumulative desperation to decide to just hold the starter button down forever.)

For the first 10 seconds, the starter and motor are turning over. It will even cough a couple of times. After 10 seconds, there is apparently a programmed internal cutoff (over temp protection?) that shuts off the starter.

For the next 3-4 seconds, nothing is happening at all (starter is not spinning), but I keep my thumb on the starter button.

After this brief interlude, with the starter button still pressed, the starter motor reengages, the engine turns over and starts up right away.

The unusual thing is that there is no variation in this process. It's precisely this every time.

It then idles a little rough for the first 30-60 seconds. If I give it throttle in this time, it is at best sluggish and at worst will stall. I can sometimes get it to drive a little, but there's a lack of power and I'm in danger of stalling. On the center stand, this happens even if the ASR is off. If the ASR is on, it is more likely to stall as the ECU decides to govern the spinning rear wheel.

I believe the idling is abnormal but I don't know how abnormal. It's my first piaggio/vespa so I have zero context. This is still much better than my carbureted bike.

After this, the BV350 operates completely normally as far as I can tell for the rest of the day.

Additional Context
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The bike had no issues for the previous owner (I believe him), and had no issues on the test ride nor on the 30 min highway ride home the next day.

It had been serviced a month prior by a Piaggio dealer. No ECU codes, test ride was good, gear oil and engine oil replaced.

It was likely sitting for an extended time, possibly multiple times on the basis that it is a 2018 and only had 1300 miles. The owner stated (later) that the fuel had stabilizer in it. I did not consider old fuel at the time and ran the whole tank through. I did not notice any engine issues or exhaust odors.

The battery was new. Possibly because it was sitting, but it had a tender connection and was about the age to be replaced anyhow.

I assume this is unrelated, but the headlight relay was bad.

Diagnostics
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I ran through the lengthy 15 sec start up procedure, let the engine run for about 5 seconds max and then shut if off. After 1.5 hours sitting, it started right up. I don't believe that subsequent fast/normal startups are due to a literally warm engine. (I can only do 1 to 2 real cold tests a day, so I've only verified this one once).

I checked the spark plug cable. I heard they crack, so I pulled it and it looked fine. To be honest I don't know exactly what a bad one would look like, but this thing looked brand new.

The engine oil had been over filled. I pumped some out to just below the max level.

I cleaned the injector. Thanks, Robot. https://www.youtube.com/watch?v=F_xDtly6KxU

I disconnected the battery for 5 min, then let it idle for 10min to let the ECU "sniff" the air.

Unrelated, but I also flushed the coolant. It smelled somewhat of burnt urine and maybe had a whisper of a brown tint, but really didn't seem bad overall for possibly being 6 years old.

Help please
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I have a service appointment with a piaggio dealer, but they're booked 3 weeks out. I thought this might be a fun puzzler for y'all here in the meanwhile and to be honest I could use the moral support. Despite promising myself I won't keep working on it, I doubt I'll be able to resist the temptation to tinker.

I'm not ruling out a random failure that coincidentally happened as soon as I bought it. However, I suspect an issue from it sitting, given that it probably hadn't seen 30 min of highway riding in some time.

What do you think the issue is? Want to tear this thing apart with me over the next 3 weeks ? Someone magically know exactly what this is and have a zero cost solution?

I bought a new 2013 BV350 and it needed to be re-flashed at the dealer (AF1 in Austin, Tx) to alleviate a rough idle / cutting off problem it had. Granted yours being an 2018 is newer but maybe this is a possibility.

Since it starts over the same amount of time every time it makes me think it has a fuel pressure issue, possibly related to the pickup in the fuel pump or the pump itself. I am thinking something to do with not having enough pressure.

Just thoughts. Hopeful you can figure this out!

As it's new to you, and may have had old gas in it for a while, it'll be necessary to clean the throttle body air bypass, and to check the injector spray pattern.

My wild guess: a failing fuel pump that takes a very long time to pressurize the fuel line so the injector works properly. Once pressurized it stays pressurized sufficiently so the scooter can be started again a few hours later.

Not 100% sure on the GTS/GTV, but the FI scoots I've fiddled with the pump package on had a pressure regulator built in. Maybe it's sticking?

I have a 2018 BV. It has done a version of this for me as well. I don't have a fix for you, I'm still unclear as to whether the issue has been corrected (but I think it has). I would keep my bike on a tender, and last summer I would go to start it up it was start and then stall. Then I would wait 20 seconds, do it again. Low idle and then up. If I gave it some throttle, it would act as if it was about to cut off, but then go. Then it would be fine.

A few weeks this happened and then a new symptom: the gauges started going wild during my ride, as if I was just turning the bike on. I bought a new starter button just in case, but never installed it, on the advice of a mechanic.
I would park it, get to work, and had a hard time getting it to start once it'd been sitting in the sun all day. After a few days of this, I was able to get it started at once, and drove it home. Engine never cut out on me, but I took it to the dealer and had it looked at. He replaced the battery, I think changed a spark plug though he admitted it still had life left. Since the battery change I haven't had an issue getting it started. Good luck and I hope you get it sorted out.

"I keep my battery on a tender all the time and it seems to have electrical issues." Start there. It usually means, I constantly charge the battery, whether it needs it or not. It's not a huge charge, but it's constant.
Unless it came with a battery tender, the people who designed the electrical system likely didn't intend for it to be plugged into the wall day and night.
And you can hide quite a few electrical issues by keeping the bike on a tender every chance you get. You don't know if the charging system is working or not, because as soon as you get it home, it's back on the tender. Until you take a longer trip and it doesn't start.
If your scooter won't start unless you keep it on atender, it has an electrical issue that needs to be addressed. It's broken.

I have a 2021 BV350 so I don't know if yours is the same, but in the correct mode it will show the battery voltage on the display. What is the indicated battery voltage during the different stages of your starting procedure, and what is it when riding ?

Well, I had some work done on my bike; they replaced a bunch of the plastics and for some reason disconnected my tender battery/heating connections as well. So my bike has been off the tender since at least the 2nd week in June when I picked it up. And in the mornings and sometimes the afternoon, when I go to start it it doesn't want to kick over. -And it's not attached to the tender. I'm not riding every day but I rode it yesterday to and from work. AM gave me some issues but it turned over. In the afternoon it took me trying it, stopping, starting again and it worked on the second try. -So what could the issue be now? It's a new battery; less than a year old.

As a reference: a Piaggio BV engine should start within a rev or 2. Always. Winter, summer, cold start, warm start, no matter.

Unless the battery is dead.
Your battery clearly is not dead when you can have the starter going for 15 seconds.

The phenomena you describe are pointing to the mixture enrichment at cold start not working properly.

If you want to fix things yourself, then check that system and leave all the rest untouched.

It's been really cool to see all of the responses and ideas. Thanks! I've learned a bunch about diagnostics from this that I hadn't learned as well from repair manuals and youtube videos. I normally like doing all of my own work on my vehicles so this is cool. In this case I went out of my way to NOT buy another project and I'm being stubborn about putting more work into it. That being said, this thread helped motivate me so I pulled the throttle body.

It was generally clean, no stickiness to the throttle plate but did have some gunky spots (first picture) on it. I sprayed a bunch of throttle body cleaner everywhere including in the air bypass. The cleaner seemed to pass through no problem. I didn't notice any gunk come out, but it was hard to spray in one side while keeping an eye on the other. After cleaning most everything else, I DID notice a bunch of gunk come out of the other non-air-bypass port (second picture).

I've never had a throttle body out where I could inspect it like this, so I have no reference here, but I didn't expect gunk. Could that gunk have been preventing the sensor(?) from operating properly causing hard starts????

Nope. I'm sure it operates better to some degree, but after getting it all back together it still had the same issue.

I think I would have checked fuel pressure next, but I had a hard time finding an affordable pressure kit I was confident would work with the BV350. I ran a tank with Seafoam instead just in case, but it didn't have an effect on the issue. I'm going to wait for the dealer to scan the ecu, check fuel pressure and whatever else they suspect. Appointment is on Wed.

Well, there no reason you should have to hold the start button for 15 seconds on a FI engine. It should start within the first few revolutions off the engine. It sure sounds like a fuel problem to me. Have you pulled the spark plug? What does the air filter look like? That gunk as you called it came from the intake side and/or the gasoline that has been sitting in the tank for a good long time. Seafoam is not gas, it was developed for 2 stroke marine engines and has no business in a four stroke engine no matter what the advertisement says. I would start by completely draining the tank and start with fresh gas. Then move onto fuel delivery system from there.

Even though it's not a lot, if you keep charging a battery for weeks at a time after it's fully charged, it can lessen it's life. Some tenders do shut off, but nobody wants to pay that much for a battery tender so a lot of them keep right on charging. If your battery is good and your charging system works like it should, and you haven't stuck all the electric doodads and geegaws on the bike you possibly can, the bike should fire right up after it's been sitting for a couple of months. Italian motorcycle electrical systems aren't known for being particularly robust, or having a surfeit of capacity to run heated armpit warmers, the biggest horn you can possibly find, and a dolby surround system. As is, short trips aren't the best way to keep the battery topped up, and combine that with the light show some people insist on sharing with the driving public, and you can keep the battery well below storage capacity for weeks on end. So overcharging and never letting the battery get fully charged are both going to shorten the life of a motorcycle battery.

I think every engine that has been running some mileage will have these "gunky" spots.
It is unlikely to cause your problem, as you have experienced after cleaning.

I'm still convinced the problem is in the mixture enrichment when cold.
Unfortunatly I do not know how that works on a BV.

Air filter is pristine. The spark plug looked ok, I think. Gap was ~0.8mm. The manuals that I have call for an NGK CR7EKB. However, an NGK CR8EB is what's in there. If I can get my hands on one before Wed, I'll swap it in there.

At 25,000 miles my 2014 BV would start and die when sitting overnight or at work. About 20% of the hard starts were the starter hitting the thermal limit.
I slapped new parts on it and couldn't solve it. Rode it like that until I sold it at 46,000 miles.
First thing, get rid of the evap crap. My bike didn't sputter and try to start. It either started or it didn't.
2ND, Install a Malossi CDI on it. It might override an ECU problem. When I sold my bike, if you removed the Malossi CDI, it sputtered and hickuped after 30 MPH.
Don't hold the start button longer than 6-8 revs. Then shut the bike off and turn it back on. Wait till the yellow engine light shuts off and try again.

My 2014 also has sluggish initial starts, but starts normally the rest of the day. It is annoying, but tolerable situation.

Bought it in 2021 w 660 miles, so some gunk build up is likely. Fuel injector has been professionally cleaned and battery is good.

Hoping handlebar (OP) comes up w a solution. Do plan on visiting local Piaggio dealer w video of initial start, but may end up like breaknwind and just live w it.

Shop says it's not holding fuel pressure; raises to 2.5 bar and then drops. Suspects faulty pressure regulator and recommended pump assembly replacement. I was tempted, but refused.

I have the regulator (and pump assembly) out already. Sourcing a new one isn't straightforward; thanks for the lead, az_slynch. While I work on confirming fitment/pressure output I'm going to try to soak the one I have in seafoam overnight.

Could these hard starts be caused by the bike needing a valve adjustment?

Just a thought keep the gas cap open maybe a vacuum issue? You ran it dry to get rid of any old gas that could be bad .

Would love to see a picture or two if not too much trouble. Have a feeling my bike has the same issue.

Bit embarrassing to admit, but after taking out the spark plug and wiping it down, it starts right up. Guess either the cap wasn't on snug enough, or soot on the plug caused the sluggish 1st start of the day.