How do you get rid of vapor lock on a 1989 Mazda 626?

Answer 1

Carburated vehicles used fuel pumps that produced very low pressure. Typically the pressure on carburated vehicles was around 1/4 to 1/2 psi. The boiling point of gasoline is actually not very high and if the fuel pump is not able to maintain pressure and/or the temperature of the fuel line BEFORE the fuel pump starts to rise above the boiling point the fuel flashes to vapor and now the fuel pump is attempting to pump vapor or the fuel between the pump and the carb flashes to vapor, the condition is called "vapor lock". Fuel pumps are designed to pump liquid. Once the pump starts getting vapor instead of liquid fuel, it is unable to maintain the fuel level in the carb. Sometimes a new fuel pump can help resolve a vapor lock problem, other times it is just a matter of heat on the fuel line somewhere. An old trick was to put an electric fuel pump on a vehicle somewhere well back of the engine. Let me know how it works out.