idles for a minute then stalls
 

I have a Quantum by American Sportsworks with 150cc GY6 engine. We hadn't run it is a couple of months, but it did have fuel treatment. It starts up and idles for 15-30 seconds, but as soon as we apply throttle it dies and then becomes harder to start. We have not been able to get it to run. Fuel filter looks ok. Any other ideas?
Many thanks.

follow up
 

So I tried a few other steps to troubleshoot, but still have same problem. Engine will run for 30-60 seconds, then dies. I hear a click right before it dies. When it's idling, as soon as you give it throttle, it clicks and stops.

1. Checked air filter--clean
2. pulled fuel filter and petcock. I thought there was a clog in the petcock because when I removed the hose that goes to the fuel filter, no gas came out. In hindsight, I presume there needs to be a vacuum (the hose coming from the bottom of the petcock) to create suction to draw the fuel out. regardless, I blew compressed air through both the filter and petcock, but still had the same problem.

Any other theories? I have a spark, and the engine does run, but have not tried a new plug yet.

thanks for any advice.

Does it shut off abruptly or act like it runs out of gas or something?

it's more like it sputters, then dies. It sounds like a fuel issue, but I can't seem to figure out where it is clogged. If it needs a vacuum to pull fuel through the hose, I am not sure how to test for a vacuum leak. I was going to rig a separate fuel source just to try it out. also thought about removing the petcock entirely, but not sure that is good for the engine (I assume it meters the flow of fuel).

do you have some spray type carb cleaner?

If so, have someone in the buggy. Take off the air box completely. Kinda give it gas to where normally it would die and when they tap the gas, give it a shot of the carb cleaner. If it grabs and revs like it should when you give it that shot, then you know you have a starvation issue and you can make adjustments from there. You need to know if it is starving or choking as a matter of fact before you can decide which way to handle it.

Don't have your face down there when you are giving it that shot either in case it back fires.

my buggy was doing the same thing and i drilled a hole in the diaphram in the petcock and then cap the vacuum line at each end then the fuel will flow. ethanol in the gas wreckes the diaphram hope that helps

so I tried a separate fuel source today, because I was fairly convinced the petcock was clogged somewhat even after blowing air through it. It had the same exact problems, with and without the vacuum tube plugged. So I am assuming the is an issue in the carb vacuum. will advise once I know more...

good luck i hope you figure it out sooner than later

Solved?
 

before I pulled carb to clean and/or install new one, I figured I would give it one last go from the top. I found a crack in the hose that leads from the crank case to the exhaust, and once I fixed that, I was able to give it throttle without it dying. Idle appears to be off a bit, but I think I can fine tune that.

after a lot of research, it appears these GY6 engine vacuum systems are simple but finicky. I think I am going to remove the petcock and go with a direct source system (and cap that part of the vacuum).

Also considering some performance uprades-- are the perf carbs worth it on these engiines? how about perf CDI's and coils?
Thanks.