Neco Di Lucio 50cc 4-stroke

[siroberts]

I have a relatively new Neco Di Lucio scooter. It has a 49cc, 4-stroke, fuel injected Chinese engine (Euro 5 compatible). Every few days, it will fail to start. It turns over, so no problem with the battery or starter. When I spray Holts Cold-Start into the air filter, it will start and run until the cold-star vapour runs out. After 5-10 attempts at this, it will fire and sustain. Then it will run beautifully for a few days, but will then fail to start again. It's like the no fuel is being allowed into the cylinder (by the injector or the electronic unit) until it reaches a certain RPM.
I have no close by bike garages that will touch small Chinese engines. Anybody got any ideas of what might be causing this, or how to fix it?

[GrumpyUnk]

A few things that are involved that you can check for operation are:
fuel pump - is it running?
injector - do you feel it pulse as the engine cranks while attempting to start?
fuel supply - is it possible the fuel supply to the pump is inhibiting fuel flow?
ECM - the computer sends pulses to the injector, most likely supplying a ground(electric) to energize the
field in the injector. You should, if it pulses ground, be able to read battery voltage on the wires to the injector. One side will get grounded, energizing the electromagnet and allowing fuel flow. A bad ground(loose, corroded, damaged) can make the injector ignore the ground pulse is it will not flow enough juice to operate the injector.
Things such as the throttle position sensor can also have intermittent connections, and the computer will then possibly think the throttle is closed, and cut the juice to the injector.
I think a quick check of grounds to the chassis of the bike would be a good start, then check the wire connectors hidden inside the headlight or under the cluster for looseness or damage. Even a loose connector on the battery or the other end of the '-' terminal to the chassis can goof up your injector system.
tom

[siroberts]

I’ll give all that a try when I get time and post back here. The bike is starting and running at the moment. I need it to fail at a weekend, when I have time to delve under the bodywork! I’ll let you know how it goes.

[FrankenMech]

Chinese Gremlins are NEVER cooperative