If you have planty of cranking, but no go, it is oftem a fuel issue. Bad fuel pump, or perhaps either not enough fuel (clogged fuel filter), or too much fuel. It sounds like carbueration. A fouled or old sensor -- O2 sensor, or temperature sensor, for instance, can throw the air/fuel mixture off enough that it won't start. May not hold the answer for you, but at least it is a start.
SteveC
October 2007