[RICHARD TILL]

is the carb a carter afb, a thermoquad or a holley? they all have the same bolt pattern and are used on that model motor. sometimes these carbs have a screen at the inlet that can get dirty/plugged. just when the motor stops take the breather off and work the throttle. check to see if the accelerator pump is pumping fuel. how old is the gas? have you pulled the coil wire to check the spark? a gas cap wont cause or prevent a vapor lock.