My zip 3 50cc starts up then stalls. It will allow me to rev a couple times then dies. Also sounds a bit louder.

Make sure the tube from the air box and the carb is connected. If its not, the motor will be much louder and it will mess up the air fuel mixture. Also, clean your spark plug, and spray some carb cleaner into the carb

I had a lot of starting and stalling problems with my Triton right after I got it. The first 300 hundred miles were miserable and resulted in one 8 mile push home.

I believe I determined the problem was the check valve off the tank that plugs into the emissions was installed backwards. I switched it around and it has not stalled in 100 miles. I don't know if your zip is the same as mine but if you take out the seat bucket on the left side of the frame on the top rail is a small 1 inch in diameter by 1 inch thick circular valve that is mounted by a rubber sleeve to the side of the frame. Just take the valve and sleeve off the frame and be sure the arrow is towards the tank. If not just disconnect the two lines and rotate the valve to the proper direction.

I hope that is your problem. I love my moped now, I hated it a week ago.

How long have you had your zip? Have you checked the oil tank (is it 2-stroke?) or the gas screen? If you aren't getting good fuel flow from the tank, it'll be pretty tough to keep the scooter running.