2014 Super 8 150 - engine dies, won't start

[jaez.hole]

I don't crave speed or have the itch to weave in & out of traffic, nor do I believe I'm invincible.  My primary reason for getting my bike was to enjoy our nice weather (summer vacation means I don't have to drop off or pick up the kids from school), and save gas at the same time.

I have less than 600 miles of riding experience (2-3 months) and I admit I didn't do my research when I bought my bike.  My first time out and my bike stalled in an intersection.  I was stopped at a light, and when it turned green I turned the throttle and it died.  The owners from the shop fixed it right away.  Since then i've also learned to never overfill the gas tank.  I wish I could somehow mickey-mouse that sensor thing to keep it from getting wet.  But yet, even after being very careful my bike sometimes will not start up right away.  And other times it will just die as soon as I turn the throttle, or even as I'm riding.

Is my bike a piece of junk?

[Porkie]

It sounds like a fuel tank venting problem to me. Fuel injected bikes for some reason don't like positive fuel tank pressure and some refuse to start until the pressure goes down. Never overfill because there is no room for fuel/ air expansion. Try this when it happens: As you take the fuel cap off, listen for the sound of air rushing out of the filler. If you hear that then the tank vent to atmosphere/ recovery system is blocked. Most times, when the pressure is released from opening the gas cap the scoot will start right up and run fine. Don't touch the throttle on start up. This venting and subsequent stalling issue has been quite common in the scooter world. Both of my Yamaha Zuma 125's had this problem as did my Yamaha T-max 500.

Sam:)

[Chris0381]

Jaez I cant help you but its serious when a brand new unmodified scooter wont work; especially a Kymco branded one.

Please dont abort this thread, let us know the updates on this issue.

This can definitely help others in the future.

Hopefully, someone can get you started on what to try first. Its a PIA and expensive to keep trailering the scooter to the shop.

[wkreps]

When it does start, how is the idle speed? Have you tried adjusting the idle so it is getting a little more fuel at startup. I found (on my 2013 Super8 150) I cannot adjust the idle too low. I don't know why but some days it idles at 1800RPM other days it idles at 2100 RPM. Spec for a 150 is 1700 +/-100 RPM. I'd rather have it idle a little too high and not have the trouble starting it, which is what happened when I adjusted it down.

[DMblues01]

Jaez,
I had the same issue with my Super 8 a while back. My tank got overfilled because a fuel pump got stuck on and wouldn't shut off when I let go of it. When that happens, fuel can vent into the emissions can and will affect performance. I had to play around with my idle setting to find a comfortable compromise for a while. After riding for a couple weeks, it started acting more normal again. It just takes time for that fuel to evap from the emission breather. And if it doesn't, it may need to be replaced. I ride mine everyday as primary transport, so mine cleared up fairly quick.

Another thing to check, which seems fairly common I've noticed, is to make sure the auto choke is working properly. Mine came unplugged once, still not sure how, and when it did it wasn't closing off when the engine warmed. It died at stops because I guess it was getting too much fuel, and not enough air.

If you find the problem, please share with us.

Duke- 

[BettinANDlosing]

I would disagree with venting issue, venting usually causes the bike to feel like it runs out of gas, if you throttle it and it died quickly there are only two things that can affect that: Mixture setting on the carb or plugged carb. I seriously wouldn't trust that shop they don't sound like they know what they are doing. Study tutorials on how to set and clean your carb. You can YouTube "gy6" carb clean, your bike has pretty much the same everything.

[Porkie]

I just looked up your scoot and found that it has a carb. There are many things that can do this. If you can get it to start, put some Chevron Techron, Searfoam or Lucas carb/ fuel injector cleaner in it and run the snot out of it and this will clean a dirty carb very well.  Venting and emissions can cause all kinds of starting and running problems.

Sam:)

[jaez.hole]

Thanks everyone for your input    Please excuse my poor choice of scooter terminology...

I have already trialed-and-errored most of these suggestions -- used the Techron, fuel injector, adjusted the idle, opened the gas cap for ventilation, etc.  It's ridiculous that I have to use these work-arounds.  But yes, this problem happens most often after I fuel up or after I've taken it off the stand and am about ready to roll out.  I do have a bad habit of revving the engine as soon as it starts up, so I'll try and practice my patience (starting tomorrow). 

So is this just how it is.. and I have to learn to deal with it?  Or is it a defect that I need to bring to the attention of the shop I bought it from?

Has anyone been able to mickey-mouse the emissions sensor?

[BettinANDlosing]

In telling you, CARB CLEAN. The only way is to open it up and clean it, once it's plugged seafoam won't work, techron won't work etc. There is no "emissions sensor". And if you take all the emissions system off your bike will LOVE you.

[jaez.hole]

Ok, OKAY b&l =/   YouTubing 'gy6' as we speak...  thanks.

[Porkie]

Techron and carb cleaners do work, not only when running but when the fuel sits in the float bowl when the bike is not in use. The thing is, the cleaners take time to work as in 50 to 100 miles sometimes. Tuners use this as a first attempt. If it doesn't work then the carb(s) has to be taken apart and every orifice cleaned out. The job is really easy except on multi-cylinder engine bikes.

Carb's have three running circuits that overlap in use: Idle circuit to the intermediate circuit to the main jet or high speed circuit as it's called. Usually it's the intermediate circuits that get gummed up.

Yes, I am an engine tuner and builder and was very active in all types of racing, maintaining my own stuff.

Sam:)

[BettinANDlosing]

I disagree, the idle jet if plugged is too small for those additives to work. Get the idle jet out, clear it with a small wire, good to go. Don't have to wait 100 miles either.

[Porkie]

Disagree all you want. I have experienced this problem many times over the years and the additives are the easiest thing to do and may work without disassembly of the carb.

Maybe the original poster doesn't have the experience to do the job. Then it's off to the dealer/ repair shop/ friend to fix it at some expense.

He's trying the Techron anyway.

Sam:)

[BettinANDlosing]

If the jet is partially plugged I could see additive doing a little, but if its totally plugged and gets no fuel flow through the jet, no cleaning activities will take place. I've had jets that I literally had to jam a wire through with quite a bit of force, I don't see anything short of chemdip doing the job chemically. Well agree to disagree, and no harm meant I'm just not a fan of additives (maybe you can tell haha).

[zombie]

F'n hate you guys!

It's most likely a mis-adjusted Idle Mix setting.