Have you dismantled your carburetor, I knew someone who unknowingly lost a small 'bolitas' that somehow regulate fuel flow in his nissan sentra carburetor.

Actually yung mekaniko ang nakawala, hayun katakot-takot na problema ang resulta. Hanggang ngayon palyado pa rin, kung saang galing na bolitas ang ipinalit wala raw makitang original.

Anyway double check for spark, vacumm leaks, and carburation. This link may help you: http://www.aa1car.com/library/carburetor.htm