Modern Vespa

OK,
Yesterday my GTS died on me on my morning commute to work, and I haven't been able to find the culprit. I've searched the forums and I haven't found anyone having this same problem, I don't think. So here's what happened;

The scooter started up fine as always, I rode about 8 miles @ 65-70 MPH till I stopped at a red light. At that point, when I twisted the throttle the engine revved but the wheels didn't turn. Then the scooter lurched forward and went but continued to jerk. I immediately pulled off into a parking lot and the scooter idled fine, but whenever I gave it gas it would start to sputter and then it just died. I couldn't get it to restart. After bribing a friend to come get me with a truck, I got the scoot home. This afternoon, I opened it up, thinking maybe I broke a belt. Not the problem. So I tried starting it up and after turning over for a couple of seconds it started right up. It idled fine and ran great under a little throttle, but as soon as I give it more, it spuddered and died. And now it won't start at all.
I've read on the forums about faulty fuel pumps and all, so I'll look into that. But my local, and only, Vespa dealer closed up shop two weeks ago, so I don't have a place to take it to other than the place that sells the chinese scooters to the university kids. They say their mechanics are certified, but I'd rather fix it myself if it's all the same. If anyone has any ideas what the problem could be, please let me know.

Couple of questions... how many miles on your GTS?

When it was jerking, did the engine sound normal, or was the engine stalling on again/off again kind of running?

Is your EVAP system still intact, or has it been properly disabled?

Along with the mileage question, what was the most recent service you've had performed?

After it acts up, if you let it sit and cool for hours or overnight, will it run fine again for a while until it reaches operating temp, or has it been terminally shitty running since the first time it failed?

David

Check the plug cap is properly attached to the plug cap. The spike in the middle of the cap is rh threaded and screws clockwise into the HT lead.

What is your LED showing when you turn the key to on. It should give a long flash and go out.

Sorry I didn't supply more info. I've got 15,600 miles on my GTS, and I haven't messed with the EVAP canister, yet. And at first I thought I might have been out of gas from the way it felt when it first started jerking, but I have half a tank. I had it serviced about a month ago (600 miles since then), oil changed and a new spark plug. I checked the plug and everything was OK there. The ignition codes fine, single light and then goes out. It started once this afternoon on the stand but died when I gave it some throttle. Haven't been able to start it since. Starter turns over but it just won't start. The more I think about it, the more I think it's a problem with the fuel delivery somewhere. I had the spark plug replaced after the previous one got fouled after the engine was removed and turned over to replace a broken exhaust header bolt. That was a month ago. And now that I think about it, the engine did start to jerk when I got it up around 80 MPH a week or so ago, but I don't normally ride that fast, I had forgotten about that since it stopped as soon as I dropped speed and the scooter ran fine.

Are those little clear bulbs on your air filter cover empty or full? If they're full, empty them and clean your air filter. Before I disconnected my evap (directions in wiki section), I drained close to a cup of excess fluid from my air filter housing. If you're sure you've got spark, which is easy to check, my money is on a fuel pump faul or clogged fuel filter (very possible at your mileage).

That was probably just the rev limiter kicking in and is likely unrelated to your problem.

*spark pkug wire (check both ends)
*failed fuel pump
*clogged air filter
*clogged fuel filter
*failed CDI
*check fuses
I don't think that it's your Evap system. My best guess is that it's the fuel pump.

Thanks for all the help. I'll post what I find out as I check everything.

First, thank you everyone for the suggestions. Now, it's been almost three months since my GTS stopped running. I've checked all the usual suspects, air filter, spark plug, fuel pump, fuel lines, etc. and they are all in working order. I've taken it to the local scooter shop and they couldn't figure out what was wrong. They tested the compression and all the factors that I previously checked and said they were fine. I bought the VDST kit from Scooterwest and ran that to no avail. It did show any faults or codes.

So now I'm at a total loss as to what the problem can be. If anyone has had this problem or if there are any LEADER engine gurus out there that can suggest something I missed, please, oh please, drop me a line.

You are looking for a QUASAR engine guru BTW. Re-check your plug wire and cap. The cap is notorious for coming off the wire: it screws on. And I recently had an identical problem with the plug cap becoming loosely connected to the plug. You want to make sure you hear and feel a positive click when you install the cap on the plug. I've got 30K miles on a 2007 GTS, and I have no idea how my plug cap became loose. It's certainly not worn out as I may have removed it 4 times since I bought the thing.

There are a lot of other dealers in your State. It may be time to bribe that friend with the pickup truck again or hit your local car rental shop and get a pickup truck for the day.

So I've been rechecking everything again just to be sure I didn't miss anything. Starting with the fuel line; half tank of fuel, fuel pump working fine, fuel lines are clean and clear, replaced fuel injector with new unit, new spark plug, checked connection on both ends of the spark plug wire, battery fully charged, cleaned the air box, disconnected the EVAP system, checked all the fuses, checked the key code, ran the diagnostic again on the computer, everything's fine, prayed, lit incense, sacrificed a spicy chicken wing (wife put her foot down, no live chicken), but it still WON'T START!!!!! I guess it's time to take it in and let the pro's have at it.

Just a shot in the dark m8 but have
you changed the fuel since it stopped
running? I bought bad fuel last year
from the local fuel station and my
scooter would not even start a few
miles down the road and after weeks
of messing/changing parts and getting
everyone i know to look at it a m8
of mine drained the fuel and replaced
it with new, a few seconds turning the
starter over and up she fired. I have
had no problems since so if you haven't
changed the fuel give it a go you never
know........hope you sort it soon......

Have you checked to make sure that you have "spark"? If not, then the coil may be the culprit....next would be a bad cdi unit. Good luck!

Do the very basics first... Does it have a spark at the ht lead?

If that's ok, unbolt the fuel injector, leave it plugged into the electrics and fuel line, drop it into a jar and try start the engine, does it spray fuel??

Do them and let me know, and ill guide you from there.

OK, so I checked both of those and it has spark and the injector sprayed fuel into the jar when I try to start it up.

If there's gas and fire, but no air....

It's got fuel and spark but maybe not at the correct time

What about checking ignition and valve timing?

Have a Manual? No here is one http://www.scribd.com/doc/21369694/Vespa-GTS250-Workshop-Manual

So it's been almost 6 months since my GTS died and I'm finally going to get it back on Sat. After all the replaced parts, checking and rechecking, and two scooter shops the problem was........... the time chain. Apparently it had jumped a couple of teeth and the timing was off. The shop found it as they were getting ready to do a tear down on the cylinder head. They said the chain wasn't loose and they have no idea how it happened but that was the cause of all my woes. They'll have it up and runnning by the weekend! Yeah!!! Thanks to everyone for your help and suggestions.

Woohoo!!! Glad to hear you are getting your GTS back and it's in working order. It's been a long wait. I hope you have some great weather this weekend and get some good rides in.

That's strange. If this is the case, they need to find out how and why the timing chain jumped. Otherwise it might do it again after they fix it.

It's going to be a cold week here in FL, in the 30's, but I'm riding anyway. The shop called their Piaggio rep who said he had seen the timing chain jump only one other time and he flew to CA fix it. That one never had the problem again. And they didn't know why that one did it either. But I'll be watching everything real close this first couple of weeks just to be on the safe side.

Who fixed it? I will be riding as well. Not as far as you though. That is one oddball/freak diagnosis. Let's ride!

You're lucky that the valves didn't hit the top of the piston. That's a very odd thing to have happened. I'm glad to hear that they found the problem and that you'll be back on the road again.

So I got my GTS back and half way home on the second ride it died on me again. This time I thought I knew what the problem was since I heard it seconds before the motor died. The variator nut came off mid ride at 65 mph and the outer driving pulley ground into the inside of the transmission casing. Right, so I thought all I had to do was rebuild the transmission and I'd be good to go. HAH! After getting it home and taking everything apart and with everything removed I tried to start the GTS up. The starter cranked over twice and whoosh.......all the hair on the back of my leg is now gone. The timing is off again and this time my beloved GTS is shooting fire out the air intake. The timing is off by a good 45 degrees now and on top of that the intake valves don't seem to be closing all the way. But on the bright side I did want to upgrade to the Malossi V4 head anyway.

Better to have your nuts flying than being burned That sucks. Also glad you weren't burned. Burnt hair smells nasty. Is the shop at fault? I would think they would be since they had her open last. Good luck. Throw some holy water on her before she goes back in

Blimey it's been a long time since the topic started and it's still not fixed!!!

Did they change the timing chain?? It must be knackered as it's too short when in good condition to jump teeth, if you remove the tensioner there's still not enough slack to move the chain around the teeth, so if it jumped it's badly stretched... So has to be past the limits of the tensioners adjustability, therefore unusable.

That's just it, the timing belt seems fine. Even with the tensioner removed I can't get it to jump teeth. The only thing I can think of is that the gear on the main crankshaft is stripped. So I'm going to replace the whole timing system. As for the shop, they said they never even opened the transmission case since it was know to not be the original problem. But they said the timing was off by about 45 degrees the first time they readjusted it, same as it is now.

Something just doesn't 'gel' here methinks. It should be near as dammit impossible for the chain to jump teeth, assuming everything is in correct alignment, and the chain/pulleys were not horrendously out of spec. Was the engine 'rattly' pre failure? Has the camshaft seized/been checked?
The variator falling apart may be a clue. Any chance the timing system has been fiddled with at some stage and re-assembled incorrectly?
Not checking the bottom end of the timing system the first time was just incompetence, there is no other word for it. You need to find a competent technician.
Unfortunately it sounds like you now have bent inlet valves
Good luck with it.

Amen.

That's what I thought too. I'm still trying to get something out of the shop but it's an uphill battle there. As for any other competent techs, there's not a one to be found within 100 miles of here. The closest was Scooter Superstore but they're out of business as of last Monday. Which, by the way, I don't understand; I am right in the middle of the University of Florida and there are scooters everywhere. Mostly Chinese 50cc's but still, not a decent tech for 100 miles? If I can get a lead on some Piaggio tools I might just have to open my own repair shop. As for my GTS, I guess it's time to upgrade to the Malossi piston and V4 cylinder head that I've wanted. Thanks for the support, you guys are what keeps me going.

That's the spirit Not much point in wallowing in disaster, rebuild her betterer and faster than before 8)

I read with interest your problem and the replies. I think everyone agrees that you have a fuel problem. No more than 10% ethylene is allowed to be mixed in gas, however, ethylene destroys rubber/plastic products. Your gas lines are being damaged by ethylene, and as the motor warms up the heat causes the damaged lines to collapse starving the motor of fuel. I believe you have 4 such fuel lines on your GTX, all accesible on top of the motor. It is a simple fix, however you may have a problem finding a replacement gas line in the correct diameter. I caution you, make sure you replace the lines with a gas line or you will have more problems. Good luck with the repairs and ride safe.

Looking back at the start of this post, I realized that it's been almost a year since my GTS has been running. It's been one problem after another. First, a broken exhaust header bolt. Then a blown rear tire. Then the mysterious fuel pump, bad gas, overflow canister thingy. That turned out to be that the timing was off. Finally, the variator came loose at speed and messed up everything, timing off again and two bent intake valves.
But now I am one part away from completing repairs Almost $2500 later, but I'm sporting the Malossi V4 head and big bore cylinder kit, new timing chain and sprocket, Malossi variator, and a Leo Vince exhaust. I can't wait!

My varator nut came off too, and ruined the spines on the crank.......
I bought another engine...and am going to do a transplant........

Did you ever get anywhere with the shoddy workmanship with the first garage? Get money back? Compensation etc?

I still can't believe they got a machine in with jumped timing, but never removed the variator to check the bottom crank sprocket to see if the locating pin had broken, fell out, worn etc...

But glad it's now rebuilt, just need to get out there and ride it now!

It lives! Finally, after all this time my scooter lives! But wait, there's a hitch. Yes it started up but lo and behold I have a coolant leak. oming from the new V4 head, the hose adapter is too small for the stock coolant hose. So once again I pulled the engine. This time just enough to get to the problem. And after a day of fooling with it, and a 1/2 gal. of coolant on the floor, I was at a loss. But today I ran around to all te auto parts and hardware stores and found a solution. I replaced the stock 1/2" hose with a 3/8" hose and everything is OK. Until.....as I'm putting it back together again accidentally overtighten the thermostat housing and cracked the plastic. But at I was flushing the system with water this time. So again I wait. At least I know it runs.

Side note; I want to thank all the guys at Scooterwest for their help and fast turn around time on orders. I think I've ordered a part or called for help almost every day this week it seems.

Finally, after 10 months of working on it, I started up, ran, and rode my GTS today. Mind you I only went around the block and down some side streets and back. But it's running. I've still only got water as the coolant while I check for leaks, so I won't go very far just yet. Once I'm sure there are no leaks, I'll switch it out for real coolant. That said, I'm pondering how to proceed with breaking in the new Malossi piston and head. Should I run it like a new Vespa and keep it under 6000 rpm's for the next thousand miles or should I do something else? I'm terrified I might break something if I'm not careful. After all the time and money I've spent I don't want anything to go wrong.

You are the most patient scooterhead.......Congrats!