Scooter dies while driving
 

I'm sure this is a redundant topic, but couldn't find answers searching forum.
Chinese scooter, 150cc with 7k miles. I could drive 7 miles or 2 blocks and scooter would periodically die, same sound as when I have run out of gas. I would try to feather throttle as dying begins, can't drive through it.
I have done the following:
Checked valves, intake and exhaust are .04 and .05.
Replaced petcock, gas flows under vacuum.
Replaced Cdi
Replaced ignition coil
Checked for spark, and spark is present
Replaced vacuum and gas lines, all look good.
Thoroughly cleaned carb and jets, carb is very clean
Removed pair system, thinking it was part of problem
Spark plug is light brown, looks great.
Tried running with gas cap off, did not change problem.
I have not checked compression, but based upon starting after it has sat for awhile and idling fine, don't think it is an issue.
I have experienced a vapor lock on gas line after it dies, perhaps not enough vacuum when running to supply gas? Thinking of trying a manual fuel switch.

Anyhow, any suggestions would be greatly appreciated.

You didn't state how soon it comes back to life. Will it restart after a minute ... or an hour?
You might try bypassing the vacuum petcock, or replace it altogether, as you mentioned.

Welcome to the forum.

Hello, thanks for replying. Typically, it would take about an hour to restart, with a few 20 min and a start mixed in. I have tried 2 different petcocks. I'll try a manual shut off switch today and post results.

Did you check the engine intake for cracks, leaks or worn gaskets? Have you tried spraying Gumout in and around the carb, vacuum lines and intake while running to see if the idle is affected? I've seen hairline cracks/almost imperceptible gaps in the intake manifold itself that expand as the engine heats up, thereby causing a vacuum deficiency.

Thanks Ebuddy, tried spraying around the carb and intake manifold, and no changes. I was curious myself about a hairline fracture around the manifold. I did, however, replace fuel pump. I kept thinking back to when it would die, there was no fuel in the filter and wouldn't restart right away because it would end up with an air-lock of some sort, after being sucked dry. So far, it is running like normal. Long test ride tomorrow. So maybe, for whatever reason, not enough vacuum was provided to the fuel pump, gas shuts off?

Appreciate the suggestions.

Thanks,
Jugdish

Start checking your ground wires and electrical connections. After it dies bounce the scooter. I'm voting for an electrical issue. Even with spark showing it could be enough to see but not really strong enough under pressure to fire.

Took a longer drive today, and about 1.5 miles, it did the same thing. Bogged down and died, and wouldn't restart. Tried to restart for about 15 minutes. Bogging sound is identical to running out of gas, or losing all spark I guess.
Weird thing is, I drove it around side streets yesterday and ran fine. It seems to be longer, continuous runs that will make it act up.
Leads me to believe it’s an electrical issue now. CDI is new, will try new coil and see if that helps.
I have read of people changing the stator and pickup coil. Gotta read about those while looking into electrical side.
I will inspect ground and electrical connections tonight.

I am having the same issues with my 2008 Qlink 150cc with 5700 miles. After pushing it half way home. I hit a curb to get of the road. I tried to start it, and it fired up, and got me home. I'm thinking loose wire or switch. Does yours have the switch on kick stand? I was going to bypas mine.

Reading this post from you, I noticed you said...."when it would die, there was no fuel in the filter". This is a problem...no fuel reaching filter, means no fuel to carb or combustion chamber. I would not waste any money on electrical components, until after I got the fuel flowing.

Does this machine still have the canisters and all of the hoses associated with an emissions control system? Is there something in your tank, blocking the flow?
Don't over think this, something is plugged, or you are loosing vacuum somewhere, or your pump(if tank is lower than carb), your petcock(if tank is above the carb), is no good, or plumbed wrong.

2wheelin, no kickstand switch for me.

Rks, correct, there didn't appear to be any fuel in filter. Although, I have since noticed with a clean, clear new filter, it's tough to see much gas flow anyhow. So that may have been a red herring. I have cleaned everything related to fuel flow(cleaned gas tank, new fuel pump, checked and replaced vacuum tubing, carb is spotless too.) I do have the PAIR system which I have removed, for fear of a vacuum blockage, with no change.
I have ordered a new stator package so I can replace the pick-up coil. Also, I have checked the ground, and it is fine. Getting close to running out of options it seems.

Set the valves to .004" inches. It seems your problem is related to engine temp, and valves are the #1 cause of warm stall.

The second thing to suspect is the coil, coils that go bad usually create a warm stall right before they stop working all together.

I changed stator and pickup coil and coil today and the same symptoms exist. Got 4 blocks down road and it died/stalled. Tried to restart and it almost started a few times, but resulted in just turning over only. Ran great while running.
Not sure where to go from here. Only thing I haven't changed is electric choke, possibly closing off fuel? Any ideas would be appreciated.
Btw, found out stator in scooter was for a 50cc engine and I have a 150. Pretty funny.

Sounds an awful like you are developing a vacuum in the tank when it dies loosen the gas cap and then try to start it. If it has the evaporator cannister that's likley the culprit or you may just need to replace the fuel cap

I have tried to drive it without the gas cap, and the symptoms are the same. I have drilled 2 small holes in the tank by the cap in case it was a vacuum problem. Gonna double check intake manifold for possible vacuum leak. Although I haven't let it idle for a long time prior to driving, it always dies when warm.