Motor stops after 1/2 mile
 

2008 Yamaha Vino 125, 16k miles

It starts easily but the engine cuts out about 1/2 mile down the road and it takes a couple tries to get it started again. It then only travels about 500 feet before cutting out. The distance continues getting shorter between starts as the engine heats up. No smoke, no apparent leaks, and no sputtering. I have been trying to track this problem down for over two months. I have replaced the carb, coil, CDI, all vacuum hoses, fuel cock assembly, and fuel filter. The fuel line appears in excellent condition. I am at my wit's end. Can someone please give me an idea where to turn next?

I'd carry a screw driver and open the drain on the carb when it stops. If no gas is flowing out you have a fuel problem. You might try cracking the gas cap open if no fuel flows out of the carb to determine if a vacuum is forming because of faulty emissions control.

When did you check valve gaps last??

Valve gaps? I don't know what those are nor am I confident/competent enough to go into the engine itself. I appreciate your attempt but it falls on unknowing ears.

I released the drain screw and a couple drops came out but only onto my fingertips (not just dripping onto the ground freely). I didn't thinkf a couple drops is sufficient gas flow. I cracked open the gas cap and the scooter ran like a new scooter. I closed the gas cap again and a couple miles down the road it started acting up again. Opened the gas cap and started to run perfectly once again. You, my new friend, have narrowed down the problem to something in the emissions system. Not sure which component but at least I can use the scooter as long as I crack open the gas cap.:cheers:I owe you a beer, Roscoe. Thanks!

Sounds like the vent in the gas gap might be stopped up.


As for checking the valves, it's a common maintenance item on these little engines and they do tend to get wonky pretty fast. Matter of fact I check mine with every oil change. It really isn't a hard process, my 10 year son does it on his gy6 buggy.

It wasn't the vent in the gas cap as I have a spare that did the exact same thing. I replaced everything but the CANISTER ASSY Part # 5CP-F4170-00-00 as it is not currently available. I removed the assembly to be sure everything is clear of cracks or holes or restrictions. One end has two nipples for hoses from and to the gas tank. The other has a tee for venting. The tee had somehow allowed two seeds from the trees to enter and clog the vent port. No idea how this could be possible but, nonetheless, the restrictions were removed and I am happy happy happy to say the Vino is running the way it is intended without a smidgen of sputter. Thanks everyone as your feedback as I closely looked at all of it. It helped a ton.

Good for you. Glad to hear your up and running again.
Do you really have to have all that stuff attached to pass the vehicle inspection in California?

More than a few of us have removed those canisters, and their associated hoses. (I did mine before ever starting the engine) Don't feel my scooter is contributing too much to global warming, considering it's averaged over 80 mpg for the last 5 years. (See Fuelly Banner below)

I would happily toss them if I knew which parts are the ones to toss and how to reroute the hoses. The motor won't be a polluter as it burns nothing but a tiny bit of gas as needed. As far as I know there is no part of the inspection related to emissions. Only VIN verification and matching motor number. Doesn't matter as I will be the only owner until it dies a happy fiery death on gramma's farm.