Modern Vespa

Hello All,

I was riding home from doing some shopping this afternoon, when about 1.5km from home, the scooter quit. I was pulling out into an intersection and it just stopped dead half way through. I was only accelerating slowly, as I had my 15 year old daughter on the back. We had only travelled about 6-7 km, had stopped twice and had only been doing about 50kmh. It was quite warm outside, about 34 degrees C (93 F). I pulled over, thinking it might be the fuel pump as it was warm, and there was only about 1/4 tank of fuel.

Pushed it the rest of the way home. Will not start. Engine turns over when starter button pressed, but there is no indication that it is even trying to catch. I can hear the fuel pump whirring when I turn the ignition on and I have topped the tank up, so I don't think it is the fuel pump. The check engine light extinguished when the ignition is on.

I then thought it may be spark, so I removed the plug, it looked fine (it was replaced about 1000km ago). I thought I would check the spark by plugging the HT lead to the plug, placing it against the engine block and cranking. When I went to put the HT lead back on the plug, the right angle socket popped off the HT lead with almost no resistance.

Could someone confirm that the right angle/socket (pictured) is supposed to be permanently attached to the HT lead? If that is the case, I suspect that a broken HT lead is the cause of the stoppage and I can order a new part and solve the issue. Alternatively, suggestions for more troubleshooting.

Regards,

Chris

Same thing happened to me. There is a little screw inside the cap that needs to be twisted down into the cable core of the spark plug wire. This is done by simply inserting the wire into the plug and twisting the plug until it feels like it,has hit bottom.

You might want to snip off a quarter inch of the cable to allow access to some fresh wire core and twist the cap back onto it intil you feel it bottom out inside the cap.

I'd you have some non conductive gel (damn, I always forget what it's called) put a dab of that on before you start twisting and it will keep moisture from corroding the exposed copper.

Thanks Trep, I was just searching while you replied. It does look like the threaded post is still in there, so I hope I am in luck.

It is very hot here at the moment, will wait till after dinner and try, hopefully it will have cooled down a little by then. Also, hope that was the problem!

Thanks,

Chris

The lead can be a bit short to start with, so if you can see the copper wire at the end of the lead, it is probably best to leave it the length it is.

Thanks for that tip. We (my son and I) tried to re-screw the cap to the HT lead - but did not cut. It did attach, but we fail to get a spark. At least we have narrowed it down some. As the lead is so short, we dropped it down through the bottom of the chassis to get at least some room to work with the very short lead - but could not see if there was exposed copper. Getting late here, so will wait till morning and try trimming the cable a little as Trep suggested to see if that works. If not, my first guess is HT lead is the problem. Any easy tricks to eliminate other probable causes as removing coil is (I think) a bit of a tricky job from what I can gather.

Thans for the help so far.

Chris

OK, trimmed HT lead to make a good connection at the socket end of the cable. No joy, still no spark. Guess next step is try to remove HT cable from coil to check for continuity, then next most likely is the coil. Will be leaving tomorrow for work and will be away for a couple of weeks, so Iguess no fix in the short term...

Edit...

Have just removed HT lead rom the coil and get a resistance of about 5k Ohms. I suspect this is correct, so next step is probably coil. Is there an easy way to check for coil function without removing it from the scooter? Could not find resistance values in the service manual. I would like to trouble shoot this out, as I don't have the cash to throw parts at it unnecessarily and the nearest Vepa dealer is 110km away (though there is a local motocycle repair place 4km away). HT coil is about $70 local.

Thanks,

Chris

Dielectric grease. The stuff is the scooter riders friend. Always smear some on electrical contacts such as the spark plug contact, ground wire connections, and the base of light bulbs.

I had problems with my coil on my 2006 GTS, though it was not a clear cut as you are experiencing (it was an rough ride with intermittent stalling).

I cannot help with diagnosis to confirm, but could well need a new coil which is a bit of a pain to fit as you do have to open up the floor boards to get at it.

One part I have had to replace twice is in fact the ht/spark plug connector - have you eliminated that as the cause yet? Its only a couple of dollars to replace and may be the problem too.

Charles.

Thanks for the input. Yes, took the HT lead out and checked for continuity. I have ordered a new coil, though I will be away with work for a while so repair will have to wait

Is there any trick to removing the floorboards? I have found the three screws beneath the rubber grip strips, removed the small plastic fairing at the rear of the floorboards and even the plastic rear cowl, but the floorboards still feel like something is holding them down when I try to remove them. I don't want to break anything else trying to fix the original problem.

Cheers and thanks for the help so far,

Chris

The floorboards are screwed together with the bottom of the glovebox, which has to be unscrewed completely to the point of being able to pull it away save for the wiring and cable. Glovebox:lower screws near foot area, inside glovebox door- 1 large black screw, screws from the front of the scooter -under the horncast (2 of them), and one in each upper corner beneath each "kneepad". PITA but not terrible.

Also, theres a large screw at the rear of the battery compartment through the floor into the steel scooter body. Battery cover needs removal to access that one.

Good luck

Thanks very much for that. I am away today and not back for about two weeks (but then have a licence renewal simulator and a university assignment due), so will report back when the new coil is in, hopefully before Christmas!

Thanks again,

Chris

Have been away from home and busy with study for the last few weeks so no time to fix or troubleshoot.

Managed to get the floorboards up and pull the coil. Replaced with new. Tried to start, but still no joy. It tries to start, as in it catches every few seconds but fails. Checked for spark. There is a spark now, but weak.

My thoughts: If it was ECU - would there just be no spark? That is what I was thinking, so diagnosis I think may be back to faulty spark plug lead.

To summarise, there is the sound of the fuel pump when the key is turned on. There is no flashing code or check engine light on the dash. Engine turns over OK, sounds like it might be firing very occasionally, but not enough to run.

Is there any basic troubleshooting for the ECU to eliminate that as the problem? I do have electronic testing equipment including multimeters and oscilloscopes.

Cheers,

Chris

sounds like a weak battery.

Thanks for that, I have the battery on charge at the moment. As everything is out of the floor of the scooter at the moment, the battery is attached to the scoot with jumper cables. It does sound like it is turning over OK, and the battery was fine when I tested under load a few months ago, but the battery has been sitting out of the scoot for about 3 weeks, and prior to that was drained a bit trying to start with initial trouble shooting.

Will re-try when the battery has more charge...

Hello everyone, and Happy New Year...

Well, new year is not so great for me, still no solution to my problem.

I have replaced the coil, the HT lead, the spark plug cap and the plug. Still getting a weak spark. I am attempting to start with the scooter with jumper leads from the battery of my car, so the problem is not weak battery. There is no check engine light. I can hear the fuel pump running, and after attempting to start, I can smell fuel from the exhaust, so I am assuming that the fuel pump is working OK. I have checked all fuses.

Looking at the workshop manual I downloaded from the WIKI, it looks like there may be other things to look at, such as RPM sensor and the electronic injector control unit (though I am assuming ECU failure would give a check engine light?).

Anyway, I don't want to just throw (any more) parts at it, I would like to be able to trouble shoot and repair/replace. Additional issue is that a Vespa dealer/workshop is over 110km away and I don't have a trailer or a truck to transport. I am also very busy with work and school (trying to re-skill as the current management are hell bent on destroying the company I work for ) so won't have much time for lengthy work until my annual leave in February.

Any advice or assistance would be greatly appreciated.

Regards,

Chris

Fuses, check all the fuses especially the ones under the seat.

Hi joedevola,

Is your scooter fuel injected? I had exactly the same experience this past September. The 300 died, so I looked at the spark plug wire, installed a new one, the new wire came apart. I tested for spark, no joy. Replaced the coil, no joy. I trucked it to a scooter shop where they instantly discovered that the fuel injector coil had opened. A new one fixed the problem.

A good fuel injector's coil resistance is around 12 ohms, if memory serves.

Good luck.

Check the voltage regulator, Had mine replaced last fall,
It caused me quite a few unnecessary replacements before discovering that it was the culprit.

Thanks for the input.

Yes, I have checked all the fuses, including the ones under the seat. I will check the injector coil, but would it cause a poor spark? The plug held against the cylinder head shows a very weak spark...

Will check the regulator - is there a way to do it when the only power is battery?

Thanks again for the help,

Chris

Have you tried giving it some gas as you crank the starter?

How can you tell that the spark is weak? Have you checked the spark when it was still running fine?

If all else fails, maybe install an evap system

...oh, and I am still waiting for your comments here

Hello Folks,

School and work has kept me away from this forum, and also from fixing my scooter problem. I purchased the Haines manual and followed the troubleshooting procedure for poor spark. The short story is it is pointing to a bad ECU.

Before I go ahead and purchase one, I wanted to check to see if replacing the ECU requires replacing anything else such as the ignition barrel or keys. I know if you lose keys you need a new ECU, but was not sure if the reverse was true.

Also, I am in Florida visiting my wife's dad. Shipping for parts to Australia is a killer, so was thinking of having the part shipped here before we fly home. I have seen one here http://www.2wheelpros.com/oem-parts/0000-vespa-gts-250-ie-super-throttle-body-with-e-c-u-assembly.html for $402. Has anyone used this vendor? If anyone has had a bad experience I will go with one of the regular vendors, but they are about $50 more expensive for this part.

Oh, will look to the thread Arno was linking to and answer his question...

Cheers,

Chris

Fixed that for you.

From your orginal post, and I will be honest I have not reread the whole thread, the wire pulling out of the cap is a know problem. I had it and fixed it with this cable made up by Scooterwest. It has shrink rap on each end. You could do this easily enough yourself.



GTS Spark Plug Wire High Perfromance
Ref. Number: 080341R
$29.95
GTS Spark Plug Wire High Performance. These are made with 8mm copper core wire with high temp Silicon sheathing (as used by NASA) rated for temperatures up to 1,200 degrees **MADE IN USA** These high output and high resistance wires are customer made and now include the original equipment NGK spark plug cap.

From your orginal post, and I will be honest I have not reread the whole thread, the wire pulling out of the cap is a known problem. I had it and fixed it with this cable made up by Scooterwest. It has shrink wrap on each end. You could do this easily enough yourself.



GTS Spark Plug Wire High Perfromance
Ref. Number: 080341R
$29.95
GTS Spark Plug Wire High Performance. These are made with 8mm copper core wire with high temp Silicon sheathing (as used by NASA) rated for temperatures up to 1,200 degrees **MADE IN USA** These high output and high resistance wires are customer made and now include the original equipment NGK spark plug cap.

Thanks for taking the time to reply. I think it fell out as a result of disconnecting it. I have replaced spark plug, coil, HT wire and cap. Have checked the resistances called for in the Haines manual for the alternator windings coil, lead plug cap etc, checked all fuses and wiring. As far as the Haines manual troubleshooting procedure goes, it is pointing to ECU.

The trouble is I am now in Florida visiting inlaws, while scooter is in Sydney, so unable to do any immediate troubleshooting if someone offers advice. Picking up an ECU while here on vacation is going to be significantly cheaper than buying it when I get home due to shipping etc.

Thanks,

Chris

Hmm, can you believe the scooter has been off the road for three months!

Life has gotten in the way of being able to dedicate a large chunk of time to this problem. Anyway, I am back at home and have a couple of days free before things get hectic again.

While in the US I picked up a new ECU (thanks Scooterwest!). I have just fit it to the scooter and programmed the UCU to the keys. Result is that the scooter now starts and idles OK (with either red or blue key), but when ANY throttle is applied, it quits. If anybody has any suggestions, I would greatly appreciate it. I am really missing being able to ride the scooter!

Thanks,

Chris

Just some suggestions but it sounds like you have a fuel delivery issue such as : vacuum leaks or unmetered air entering the intake manifold , faulty oxygen sensor(lambda sensor), dirty fuel injector, or low fuel pressure to the injector (weak fuel pump, restricted fuel filter).

I can't contribute since I'm not knowledgeable, but I want to say how awesome it is that you have such great perseverance in working with this problem!

My neighbor's ET 4 was doing that, starting but dying when you twisted the throttle. Turned out to be the fuel tap but its carbureted not fuel injected so I don't know if that would make a difference.

That definitely makes a difference.

I have that same problem with my derbi gp1. I have to let it run for a while before it will engage the throttle. Stupid 2 stroke. Not exactly sure what causes it. Once it stars running it works just fine.

I guess I am at the point where all of the probable issues are stuff that cannot be tested with a multimeter and require the specific Vespa test equipment. As I live about 110 km (65 miles) from any Vespa workshop I was hoping to solve the issue myself. Obviously I have reached the point where I am going to have to borrow or hire a truck or trailer and take the scooter to town for expert assistance

Thanks for the input and help along the way though.

Chris

Best of luck with your issue. I really want to know the outcome.

Thanks. The plan is to hire a utility/light truck probably Wednesday next week to take him to a Vespa service centre in Sydney. When I find out what the problem is I will report back.

I bet that if you call the dealer in Sydney they will either have their own truck service or know of someone who offers it. The important thing is that if you or the service you hire isn't proficient at loading and tying down a scooter for transport, bad things can happen.

I did end up hiring a ute to take the scooter to Sydney. My driveway slopes down a little and flattens out at the garage, so a 2.5 metre plank and a bit of a push had the scooter on the back with no trouble. A couple of ratchet straps and she was secure. Unloaded in Sydney with the help of the mechanic.

Now, the report. It is running, but we are not sure what the problem was...

Short story, the mechanic had the same issue as me. Would start and idle, but would stop as soon as accelerator moved. He 'checked the wiring' and replaced the spark plug, and it works. The plug he removed was an iridium that was extremely dirty with black soot. When I was checking the spark, I was using a spare plug so as not to damage things with constant removal and replacement of the plug. When I replaced the ECU, I did not bother to re-check the plug. I guess the constant starting attempts must have gummed up the plug. So, my guess is the ECU replacement fixed the problem but the plug was fouled, or 'checking the wiring' (something I had already done), had fixed some bad connection.

Will leave the scooter in Sydney a while to make sure it running OK before driving it back to the Southern Highlands...

Good to have it running again!

It's always the last thing you check.

Glad it's back in working condition!

Glad to hear it's sorted.

It's the little things...