I have 509 CI 250 blower motors with a single carb setup. Right now there is a mechanical fuel pump mounted to the sea pump and a electric pump powered through a oil pressure activated switch feeding the mechanical. My question is why use the oil pressure activated switch? My original thought was that if there was a loss of oil pressure the motor would not run however the mechanical pump pulls enough fuel through the electric pump to run the motor, plus if the bowls were full the motor would run long enough to hurt it anyway.

Is there any benefit to having the oil pressure switch to activate the electric pump?

Thanks

Well it is just an easy way to power it among other reasons. The pressure switch can be replaced with others that close at various pressures, I think about 10 to 20 PSI is common.

It's a safety device. It prevents the electric pump from flooding your engine compartmnt with fuel if the engine dies.
And e all know holleys never have stck floats

Very good explanation. That is one thing I did not think of. Thanks.