My battery is in the trunk, where most should probably be. That makes it real easy if you also put the pump back there where it needs to be. The relay is like a remote switch, so the more direct the power-side is, the more clever the installer is shown to be.
As to your question, the battery is the usual source on account of it's voltage is regulated,to something the pump can handle. Alternator juice is usually a volt or two higher.Sometimes close to three.
I wouldn't pull power from any circuit after the ammeter, cuz you know, the bulkhead connector is old,tired, and was barely adequate to handle the factory load.........when new.
And if you're just using the pump as a primer, if you wanted to be really clever, you could run the signal side off the brakelite circuit,or the running lites,lol. But if this is in fact what you are attempting, then you need a pump that was made for draw-thru, so the mechanical pump can continue to pull fuel, after the primer is turned off.
"Need to pressurize the system before start".
Is this typical in Wisconsin? Or is your car one that stands for long periods of time between outings? Or ?
