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supereal · 06-24-2019, 02:54 PM

More often than not, "vapor lock" is due to a weak ignition coil. As the coil temperature increases, resistance goes up, and current goes down (Ohm's Law). We leave the stock pump in place and use the electric pump to top off the carb after a long storage, or the evaporation due to heat soak when a hot engine is shut down. I use a regular toggle switch for he electric pump (an Airtex) wired to the accessory post of the stock ignition switch. This way, the pump is disconnected when the car isn't being used, and if you have a spring switch, and need the electric pump to get home, you don't have to drive with one hand on the switch. This setup,on my '47 has been trouble free for the 25 years of owning the car.

06-24-2019, 02:54 PM	#9
supereal Senior Member Join Date: Jul 2014 Location: Iowa Posts: 1,634	Re: Vapor lock question More often than not, "vapor lock" is due to a weak ignition coil. As the coil temperature increases, resistance goes up, and current goes down (Ohm's Law). We leave the stock pump in place and use the electric pump to top off the carb after a long storage, or the evaporation due to heat soak when a hot engine is shut down. I use a regular toggle switch for he electric pump (an Airtex) wired to the accessory post of the stock ignition switch. This way, the pump is disconnected when the car isn't being used, and if you have a spring switch, and need the electric pump to get home, you don't have to drive with one hand on the switch. This setup,on my '47 has been trouble free for the 25 years of owning the car.