Modern Vespa

Hi There,

Thank you in advance for taking a look at my thread, I tried searching the forum for related issues but the search function was buggy.

I have a 2007 Vespa GTS that is ridden on average 4 times per week as my daily driver [10 miles round trip]. It used to be every once in awhile the machine would haver an issue turning over when started, it would crank and then die. The problem subsided for about a year and a half without any meddling on my part. I figured it was bad fuel.

Recently, I find that under acceleration the GTS will sputter and decelerate or at times completely lose power from the motor. The machine itself is still being powered by the battery, though the engine is cut off. Here and there when I approach a stop light and idle waiting for the green, the engine will die. The same goes for when turning over from a cold start. It will fire up, rev and then die. This is all very inconsistent, but it is happening more frequently.

The GTS has 24K miles on it, and from my understanding this model was not affected by the fuel pump recall.

Does anyone have the slightest idea if this is a fuel pump issue or something to do with the relay? Is it a completely unrelated problem? Any help would be greatly appreciated.

Thank you again,

HermosaBeachGuy

I have had the same symptoms on my 2007 several times over the years. In each case it was solved by installing a new battery. Even if the old battery cranks the engine properly, the electronic fuel injection system will not run properly on an old battery.

Cheers and good luck,
Bob

You can have a dealer confirm whether the fuel pump recall has been performed on your GTS . Some of your symptoms don't seem to match the original fuel pump issue, however. Given the age of your scooter and past usage, it seems to me that the issue could be a dirty injector.

Thank you Bob and Dooglas for your feedback.

Concerning the battery, it is a brand new lithium battery installed two weeks ago. I did test the voltage regulator after install and all the readings seem to be in order there.

The Vespa has never really sat since it was in my care save for 2 times when I have surgeries and was off the scoot and moto for 8 weeks. The Vespa cranked and ran fine after those two stints. Regardless, I will prime and clean the fuel injector next to rule that out.

The only other thing I have recently done to the Vespa was change the gearbox oil. I followed the guidance of the owners manual. I cant imagine it was overfilled as it was drained completely and filled to the specifications outlined.

Anyhow, thank you again for your time and consideration. I will let you know if the fuel injection cleaning takes care of it. It could just be poor gas. Chasing these ghosts are so much fun!

The early GTSs had a common problem with the kill switch. Water gets in and corrosion makes the switch intermittent and might be a cheap place to start.

Did the fuel injector cleaning work? - Going back to the fuel pump, have you ever run out of fuel or let the scooter stand for any length of time with hardly any fuel in?

The fuel pump is located at the bottom of the fuel tank and needs to be submerged at all times as it is cooled and lubricated by the petrol.

The fuel pump could have been damaged if it has been allowed to dry out.

Just another thing to consider in diagnosing the problem you have.

BTW, you will avoid some problems and questions in the future if you put the model of your scooter in your profile so that it appears to the left in your posts. I know you identified your scoot at the start of this thread, but that is just an easy and reliable way to do it. Good luck with addressing your power loss problem.

Sounds like a failing fuel pump or possibly a broken injector. If it's the pump, it will likely get a little worse as it warms up (both weather and bike).

You can visually inspect the injector for cracks. Do a search here for more info. 250's with blown/old suspensions are susceptible to this. The injector slams up into the seat when you go over bumps and eventually breaks.

You may also have a slight vacuum leak. Run the bike and spray carb cleaner around the intake and injector and see if the idle rate changes.

Thank you all for your insight. I haven't had an opportunity to sort out the fueling issue further as I have newborn on the way and the "Honey Do" list for baby is impacting wrenching opportunities. I will pass back an update as soon as I have time to address this further.

I ran the scooter for 20 miles round trip just a few days ago and nothing presented. So I'm sure this ghost will present itself again if I do not get it first.

Cheers,

HermosaBeachGuy

I have a 2007 GTS and have experienced some similarities. Check engine light comes on and sometimes idle gets rough once it's been running for an hour, setting Oxygen sensor codes, and it cut out on me once very briefly. I found the injector connector cracked and loose as previously described. The replacement should be here today. Hope that fixes everything!

did it fix it?

Yes. The part showed up today. I installed it, cleaned the throttle body and idle passage, and capped off the canister vacuum port on the intake. I think the canister was saturated anyway and it seemed like a good time to take care of it. After that I cleared codes and deleted adaptive data.

A 60 mile ride confirmed it has never run better!

How?

I used IAWdiag. I can't remember the exact wording for the option that does it (stored data?). You can also disconnect the battery for a few minutes.

sadly IAWdiag apparently doesn't yet work with HPEs


although I've often read about disconnecting the battery (most say 30-60mins) I've also read that that doesn't work. Maybe works with older generation ECUs but not current? Here's a post about a 2020 Primavera 50
https://modernvespa.com/forum/post2501064#2501064

Yes, for the HPE you have the same challenges I have with my Euro 5 Guzzi. A solution will come along. Always does.

Hi All,

I wanted to give you an update on the status of my fueling/stalling issue.

Before jumping into cleaning the fuel injector I thought to check the EVAP hose and clamps to see if they had dislodged or simply eroded given the age of the Vespa [2007 and 25,000 miles]. I had also heard that sometimes older shocks that compress quite easily under dual passenger load with potholes/speed bumps can dislodge the connection as well.

To my surprise it was not that the EVAP hose was completely broken, but that the previous owners or "mechanic" had drilled a bolt into the opening of the line to plug it. [attached imaged for your viewing pleasure].

It is beyond my comprehension how someone might think that this was the appropriate fix.

Anyhow, after 2 worm clamps and 2" of nylon braided hose we are back in business running/idling quite smoothly.

I have no clue what the impact of this may have had longterm on the motor, I suppose only time will tell.

Thank you all again for your thoughtful consideration on trying to remedy this issue.

-HermosaBeachGuy



[/img]