[dsraven]

Check down throat of carb to see if accel pump squirts fuel. If not it's likely the carb bowl is empty for some reason.
Dirt in carb I let needle causing restriction. Dirt in gas tank outlet causing restriction. Collapsed rubber fuel line under the floor at the gas tank end. Dirt in fuel pump causing valve malfunction (some of these pumps come apart so you can clean them out). Plugged fuel filter if it has one.
Disconnect line at pump inlet and extend it so you can put it into a catch jug. Then blow into the fuel tank and see if you have nice clean fuel flow at the jug. If using air compressor be careful not to overdo the pressure
Fuel pump pressure/volume test if the fuel line test looks normal pull the lid off the carb and see what's in the bottom of the bowl
Plugged muffler usually let's engine start and idle, depending on how bad its plugged. With vacuum gauge installed engine will show vacuum at idle but then drop off vacuum as engine is revved up
Sounds like more of a fuel starvation problem to me. Also check advance mechanism on distributor, vacuum and centrifugal. Sometimes centrifugal advance is stuck, siezed or has lost a spring