Starts and dies

[Motoman]

I bought my son a SunL 150cc scooter and all was well until it decided not to start. It will crank over and startup but then die like its not getting gas. I'm getting ready to tear into it but thought that someone else may have had this problem and could give me a few pointers on where to start. The scoot has less than 100km on it. Any help would be greatly appreciated.

[IronFist]

Try idling it without the gas cap, it might be your gas cap gasket?

[Motoman]

It won't idle. It runs for about a second after you release the starter button, then dies. Same thing every time.

[IronFist]

Take the gas cap off and try again.

[Motoman]

Took the cap off and tried it but now it's not trying to fire at all. Is there an automatic gas shutioff and is it fused? I'm thinking that my problem may be electrical.

[IronFist]

You could try pulling the plug, from the cylinder. With the plug in the cap, hold the electrode end of the plug against the motor and kick start. Wear rubber gloves and try to dim the lights if you can. If you don't see a nice fat blue spark jumping from the plug, you have an electrical problem. Keep up the updates. Hope you get it working.

[Cal25]

Maybe one of those with a vacume operated petcock?

[IronFist]

8O ???

[Motoman]

Well it's not electrical. It will start up and die a second or two later. I think that my problem is the same as LadyDi, the funky little vacuum valve not letting gas go to the carburator. I'm going to bypass it tomorrow and if it runs, I'll get a manual shutoff valve, if I'm getting vacuum on the line.

[IronFist]

Cool, hope you get it going.
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Ride to live, so you can ride tomorrow.

[Motoman]

Thanks IronFist. I'll let you know how it turns out.

[pedez2000]

could be the jets too we change alot of those jets on the sunl 50 and 150

the 150cc run great with a 117.5 120 122 main and a 38-40 pilot jet.

best seller are 120 main and 38 pilot.

[tigertamer]

Originally Posted by pedez2000

could be the jets too we change alot of those jets on the sunl 50 and 150

the 150cc run great with a 117.5 120 122 main and a 38-40 pilot jet.

best seller are 120 main and 38 pilot.

If it ran good new, I don't think a new jet is the answer. There may be some improvement with a new jet, but a poorly sized jet shouldn't "go south" overnight...It's not running at all!

How is the petcock bypass working?

Keep us posted,
Tigertamer

Oh, by the way, watch how you spell petcock, because if you use a hyphen, you will be censored!

Here's an example I typed with the hyphen: pet-cock

Dirty little computer minds...
Tigertamer

[Motoman]

Finally had time to check the SunL and found that I have the same problem as LadyDi. Petcock valve is non functional. I bypassed it and went to the carb and it starts and runs fine. Once I got it running I checkd for vacuum at the valve and I have that. For some reason the valve is not opening to allow gas flow. I think that I will go with the mechanical on-off valve.

Thanks for the help and suggestions and thanks to LadyDi for her write up.

[IronFist]

Thanks Lady Di