I want to be able to add a Holley electric fuel pump to my car's mechanical system. Will fuel free-flow through the electric pump with the pump turned off?
In other words, I don't want to hear that whiney pump all of the time, only when I'll need it during full throttle runs.

Bump... anyone?

My Carter mechanical pulls thru the Comp 140,not sure if Holley is the same or not.

Jimmy,
It will work fine. I have several customers that have it set up that way. Use the mechanical pump by itself on the street and just turn on the electric at the track for some insurance.

The Carter 172 will pull thru the Aeromotive 2000 on my '70. I only switch on the electric at the track.