Can bad fuel cause a vapor lock in the fuel lines/ pump/ carb?

Have you had a vapor lock before? What were the signs and what did you do to cure it.

Thanks

what are your symptoms?

Usually it shows up after a long hot run. Shut down and it doesn't want to refire. You can help by idling the motor for a while to let it cool down and open the motor hatch to let are circulate.

the time of year at which the fuel is made affects vapor lock greatest. if you fill your boat up late in the year when it is cold before storing it to avoid condensation in your tank, you are more likely to get vapor locked until that gas is run out of the system. butane is a byproduct of refining gasoline. it isn't worth much money to sell. since butane has a boiling point (depending on the distillation process) of around 30*-50* oil companies tend to "hide" more of it in gasoline when it gets cooler. they make more money that way since a gallon of gas is worth more than a gallon of butane.
the more butane in your fuel when the temperature gets hot outside, the more likely it is to vapor lock. actually, the butane starts boiling and goes to a gas state and can't be pumped until it weathers off. the best way to combat vapor lock is not filling your tank up in winter. spacers under your carb that don't transfer heat are a good idea, aluminum intake manifolds transfer more heat to the carb from the heads than cast iron manifolds also. electric fuel pumps are better than mechanicals that are attatched to the block because they won't transfer heat from the engine block to the fuel. hope this answered your question.
Fran