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I am installing an electric pump on my 49 just to help with cold starts.

Car is positive ground, RED wire to ground or
BLACK wire to ground?

You guys (or girls) are the best!

Typically Red is positive so that wire would go to ground on a positive ground car but just make sure to look for definite markings or instructions by the mfg. Be sure to put a fuse in the feed or negative wire and preferably before any on/off switch controlling the pump you might have placed under the dash.

Exactly what Howard said. Car is positive ground so hook the positive wire to ground.

For fusing, use a fuse 1 size larger than the rated load, and carry one 2 sizes larger with you in case the first blows from inrush current. For example if the rating is 2.1A I would fuse it at 3A and carry a 5A spare just in case. Or on the instructions it might give a fuse size.

Fuse the ungrounded (negative) size and connect it to the ignition terminal using a ring crimp on the wire. Don't splice the factory harness. Or if it's just for priming, maybe you would prefer to hook it to the battery terminal on the ignition swutch instead.

For inline fuses I like to use the modern bladed style since they are cheap, ubiquitous, and easy to identify by color. Though if you already carry a glass fuse kit you may as well go with that style.

I have a blade style fuse wired into the supply wire.
I am going to attach it to the end of the negative battery cable at the starter for the installation.
Before I install the pump, I’m going to test the pump from the battery using the fused line so that if I’m backwards, it will only blow the fuse and not burn up the pump.
The fuse is 10 amp, what Airtex recommends.

Does this sound okay?
,

Paul: IIRC Airtex instruction suggest for positive ground installations to insulate the outer case from the mounting ‘P’ clamp. Please confirm. Not a big deal, I used thick double sided tape . . . it’s been working for years. dp

The fuse size and type is OK but I would not recommend powering it at the solenoid directly off the battery because it will be energized all the time. Going thru the ign sw would provide much more safety when the car is unattended.

You did not mention if you were going to have a separate on/off switch in the line. Even if you do have a switch you could forget to turn it off but if no switch, IMO always on power is an invitation to trouble.

With pump always powered, should a worse case happen and say a float valve in the carb was not fully shutting off flow or if the electric pump is placed in the typical way where the mechanical pump is still in the line, if the diaphragm in the mechanical pump ruptured or valve leaked the electric pump would be able to pump and you could wind up with a tank of gas in places it should not be.

You for sure want it "double switched". Pulling the power from the ON side of the ignition switch, and then thought a underdash mounted toggle.

That way the pump only get power when the igniton is on and the dash switch is also on.

Another reason for the double switching is for the case where you want the igniton on, but you don't have the motor running. You don't want to the pump continously running in that scenario.

Mine are marked -6v or +6v and have only one wire with the housing being ground. They are from the '60s or '70s, though, so apparently later ones have two wires. None of these are installed on any of my cars as I've never found the need for an electric pump.

Thanks for all of your help and advice.
As the British say, I think I have it all sorted out now.

By the way, Airtex call s for a 3 amp fuse, not 10.

So, another trip to Auto Zone!