Modern Vespa

Hi guys,
Several months ago I had a thread going where I was having an issue with my GTS loosing power while riding. It looses all throttle response and then sputters back. Once in a while it will stall completely. I had checked the spark plug connection and I even removed the whole overflow canister system which I thought had fixed it, but it's back. It definitely seems to be some kind of fuel delivery issue and I'm wondering if it could be a problem with a clogged fuel filter, water in the gas tank, etc? Thinking of running to autozone or something and picking up some dry gas or fuel cleaner or something. Especially since I don't ride often recently... it's too darn hot for Toreador Pants in houston. So it does sit, sometimes for weeks at a time. I keep it plugged into my batter tender and try to at least run it around the block once in a while. But this problem was happening even when I was riding it several days a week in the spring.
Any more ideas?

Dennis-

If the two steps you took (plug & canister) solved the problem last time. then start with doing that again. Then, if that doesn't fix it, treat your fuel for water. If no joy, then check each and every part of the fuel delivery system - one component at a time.

The only way to trouble shoot and know what was the real problem is one item at a time. Or, simply clean, replace, adjust everything you can think of and maybe one of those will fix it. That will take much more time, and you really won't know what was wrong for future purposes.

Al

Dennis, if you want to try something simple first, buy some seafoam and add it to your gas tank. Then run your scooter through. Sometimes during the winter people have a problem with the gasoline in their tanks going bad. Preventatively you'd want to add stabil to your tank if you won't be riding for a while, however, after the fact, adding seafoam might help you now.

I actually just returned with two cans of the stuff!
I have to add this to a pretty much empty tank, right? Mine is almost full.
Is there an easy way to drain it?

1. When you removed the canister system, did you run the overflow line from the top of the gas filler opening towards the ground? (or did you plug it?)

2. Did you plug the hose that ran from the canister to the throttle body? ( the hose coming from the throttle body)

3. Have you checked your air filter to see if it's clear of oil & gas?

4. Spark plug wire screwed tightly into the cap? And on the other end, pushed firmly into the coil?

Other than that, I would say that either:
a) the fuel injector needs cleaning
b) or you have an erratic fuel pump that may be getting ready to go
c) you have an erratic coil that may be getting ready to go (we've had several of those reported on the forum)

Let us know what you find.

Any additive I have put into a fuel system had instructions printed on the container. While "Tim the Toolman Taylor" would advise otherwise, I'd say try doing what the label says.

Al

Yes, follow what the label says on the bottles of seafoam. I don't believe you are meant to drain the tank and run only seafoam through it as I don't think the engine would run on just seafoam.

1. Same...Seafoam treatment and maintenance there after.

2. Just posted this on the overflow hose to evap. canister to reduce pressure build up in fuel tank.

https://modernvespa.com/forum/topic50298

Note: The evap. hose disconnect (which has been covered in Wiki) varies from a carburator to fuel injection.

Interesting that while at our informal clinic yesterday one of our group point out that the problem could be the coil he's getting this checked out.

As pointed out in previous post.

c) you have an erratic coil that may be getting ready to go (we've had several of those reported on the forum)

XLR8

I add seafoam to every tank or at least i try to. Seems to make it run a little better. Which might be in my mind but in the end it can't hurt anything.

Sorry, had to run out for a bit.

1. Run towards the ground, left open.

2. Yes, plugged and I checked that it is still plugged.

3. Have not checked the air filter recently because it's such a PITA to remove the engine guard and fender to access all screws on the filter box. But the rear bulb is filled with brown oil.

4. Seems to be ok. Hard to reach the other end of the spark plug wire.

Although it's a pain, you should check the inside of the airbox, just to make sure that's not causing your problem.

Ok, i checked. Other than a little oil soaked into the very base of the filter, it's pretty darn clean, actually.

O.K.
Then, if the spark plug wire is firmly seated on both ends of the wire and the cap is tight on the spark plug, that leaves a dirty fuel injector...............or an erratic fuel pump................or a coil that is going bad.
The odds are that one of these is the culprit. Nothing else comes to mind that would cause these symptoms. If the fuel injector cleaner doesn't work, you may have to take it to a dealer who has a diagnostic tool.

Ok, thanks for helping narrow it down.
Any tips on reaching the non-spark plug end of the wire or how to tell if its connected properly?

Although it is rare, there is such a thing as an intermittent sparkplug. I just replaced one on a chainsaw that would not run for more than 30 seconds from cold.

I had your problem on a GTS 250 and successfully gave it the sparkplug/fuel treatment approach. Be sure to gap the plug properly.

Another problem that shows up (on older cars with the coil mounted off the engine) is a corroded ground return from the engine block to the coil ground after a couple of years. The high voltage wire between the coil and the spark plug is only half of the circuit. The ground return is the other half. The cure here is to run a ground wire directly from the coil ground to the engine ground. It will be interesting to see if this affects modern Vespas as they corrode over the years.

Cheers,
Bob

Well i tried the Seafoam thing and i'm still having problems.
Yesterday it stalled at least 4 times on the way home (10 miles).

So tomorrow I drop it off at my Vespa dealer.
He said he'll probably have it a while. He has a couple other ones in for fuel pump and fuel injection issues.

And unfortunately I'm passed the one year warranty. Only 2300 miles.

Before you take it to the dealer, check your battery. If it's low on charge (even though, it's enough to start the scooter) this can cause these types of problems. I just received a PM from a member that I have been assisting with these same types of problems and it was his battery.

Good luck!

Thanks xlr8, it stays on a battery tender and the tender says it's fully charged. Maybe it's going bad? But I've had this problem for quite a while now. It's about 18 months old, only 2300 miles.

Test it with a multimeter. Then start the scooter and test it again while it's running. Then, shut it off and test it again.

As I said in the other post, a member with a GTS had your same symptoms and after exhausting all the other checks, it turned out to be a battery that was going south.
Good luck!

So i brought it by my dealer today and they had me bring it around back to the garage. We talked about what's going on and Chris was a bit confused as the symptoms were pretty weird. Fuel pump was fine. No fault codes. And when it happens seems to be completely random. So he reset the computer because he said he's seen some similar issues that throw codes. No codes to be found on mine be he figured he'd reset it anyway.

Then, and XLR8 you're gonna like this, he pulled the battery out and it was low on juice. About half an inch below the minimum line. So he grabbed a new battery, made sure it was fully charged, and through that in there. Then he took my old one, filled it up and started charging it.

So now he wants me to ride it around and see if either of these helped the situation. When I got home the other day I through in more seafoam too. It didn't stall on the way there (only a 10 minute ride) and no stalling on the way home... stopped at the grocery store too. And he didn't charge me, either! He doesn't want to start pulling the gas tank or any of that yet because it involves so much work. Figured he'd get the easy stuff out of the way first.

I'll report back when i know more...

Hey, that's great news. Since it immediately started running better, I would be surprised if that wasn't the problem. I would strongly suggest that you just go ahead and replace the old, "wet battery" with a new, sealed, maintenance free type. Then, you don't have to worry about checking the water level, over filling or run-over battery fluid that will corrode the metal area around the battery.

Thanks for the update!

Hi Benny,is there a UK version or something the same we can use "over here" lol Thanks Bill

I honestly don't know, hopefully one of the UK members can answer this.

I'd advise getting the latest ECU update done, or at least having the latest one reset. Some say disconnecting the battery for 20 minutes will do the trick - I have never heard any real evidence this works.

I have a stalling issue with my GP800 on throttle off and clutch disengage - Piaggio are stumped on it. So it's not model specific as a problem, though the solutions probably are.

XMAN do you have a UK version of Amazon? If so go to the site and enter seafoam and see what pops up. You can buy it on amazon here so maybe they have it there. I can call the company next week for you and see if they sell it over there. It's to late in the day because of the time zones but i'll check for you monday.

He didn't say anything about updates, but he did reset my computer.

Rode into work this morning and not one hiccup! This could be good...

That sounds promising, fingers crossed for you Dennis.

Thanks, Benny!
We'll see. This evening's ride home in the 100 degree heat and humidity should be interesting. Last thursday it stalled on me (or at least tried to) 4 or 5 times in that 10 mile trip home.

Made it home and it was smooth as butter the whole time! 8)

Sounds like it is fixed!