Modern Vespa

Sorry if I should put this in the other thread, but it does seem a bit different. As you know I have had breakdowns recently. Bike just dies after being ridden for 20+ miles. Seems to happen when hot. Has happened twice. I have been told it's most likely the fuel pump/heat (I am just awaiting on the dealer to come get it sometime this week)......In the meantime as I am awaiting them - I have had zero breakdowns. My ride to work is about 10 miles each way......but I have been aware of not really going too far. I work in NYC which is about 25 miles away and that is when it happened......at the end of the ride when bike is hot.

I have been testing the bike by letting it idle (fan goes on/off) and it does idle.....but after about 40 minutes or so- it just stalls out etc while idling. Then doesnt start again until cool.

Is that normal for it to stall out if left to idle for so long??? I am wondering if my woe has corrected itself or something or if the stall while idling is just a sign that there is indeed something wrong.

I guess I would rather not give the bike back to the shop, but if there is indeed something wrong with my fuel pump (again) I of course want to get it replaced.

Not normal IMO.

To be honest, I've never left mine idling for that long?

IMHO, I wouldn't base too much of a diagnosis on 40 minutes of idling. I think it's unpredictable what could happen. (I wouldn't be surprised if any of my small engines stalled after idling that long.) If I suspected the fuel pump on "hot" days I'd be more inclined to track the ambient temperature and the miles I'd ridden *.

Again, in my opinion, your problem is your fuel pump. I could be wrong.

* and perhaps the amount of fuel in the tank, as I've read that fuel has a cooling effect on the pump and stalling is more likely if there's only a little fuel remaining.

Tank's full......Yeah, my dealer said he is pretty confident it's the fuel pump - I just wish he thought that originally rather then the ECU that "fixed" it but when it happened again he seemed pretty confident that is what the deal is.

Looking forward to getting it taken care of this week.

I've let mine idle for long periods of time to test the fan, never stalled out.
My guess, fuel pump, charcoal canister or valves.

My guess.

You might want to do some research as to the advisability of letting an engine idle for 40 minutes. It can cause excess wear, shorten the life of the cat, and likely drains the battery. With a single cylinder, it's not surprising that it stalls if you let it idle for an excess amount of time.

No, that is not normal.
If your cooling works as it should, and apparently it does considering your fan goes on and off, the engine should keep on running on idle for hours, until it runs out of fuel.

Extensive idling is not great for an engine and 40 minutes is a mighty long time.

The motor of your Vespa is engineered to operate under load, meaning with you riding. Neither the engine cooling nor the lubrication perform at their peak while idling.

I understand that, I was just trying to repeat/duplicate a failure that happened recently before I allow my dealer to come pickup the bike and replace the fuel pump. It's not something I do often, just did it twice as a test.

I know……was just trying to duplicate the failure prior to allowing the dealer to come and get it.

The verdict is fuel pump. This is what I was told

"Yeah so when the pump is faulty and the bike gets hot, the pump expands and essentially starves the bike of fuel. Thats's why you need to wait for it to cool down before it starts again. That's whats happening here and we see it happening in other bikes as well with the same condition as yours"

Damn! This will be my third fuel pump at 7200 miles!!! factory one went caput at 400 miles…….

Anyway - hopefully this is it!

valves also expand with heat. I'm not confident that they have checked them (only because you problem persists after multiple pumps)

Hopefully they can replace it with a "new and improved" one that lasts much longer.

Thanks for the tip. I have just emailed and brought this up to them and asked them to look at the valves too

Just spoke with them - He said they know to look over the valves, but at my suggestion he will mention to the techs.

I wonder if 40 minutes of idling is going to kill a good fuel pump.

I won't do that. That was just to duplicate what happened a few times prior to replacing the pump to make sure that is what it is.

Picked up my bike with the new fuel pump today at 11:30. Was on it until 6pm pretty much non stop. No issues. Two of those hours towards the end were in bumper to bumper traffic getting out of NYC with the fan going on and off all the time. Seems to me that it was the fuel pump since the conditions for heating up etc couldn't've have been any worse and the ride all in was 40+ miles. Feels good to have my bike back