After running awhile scooter dies

Hi first timer here. I am working on a 85' fa50 Suzuki. The owner says he can drive it about a mile then seems to die like no fuel. He tries starting it and gas comes out of the trail pipe. He had somebody else look at it about 2 yrs ago. The other guy said the only thing he could think of was the petcock. Well I just pulled it apart and everything looked good including the diaphragm and O-rings. Any other suggestions. I would really

appreciate them.

Thanks

Thanks for the info. I did some more checking it seems the coil, cdi box, and rectifier checked out to be bad

from sitting. I can find the coil, rectifier, and I ordered them. But having problem for CDI box. Does anyone

know where I can find one at a decent price. That way I can get this bike done and go on to the next prolem.

Thank you