Convenient underhood source of switched power?

Weather in Geneva has turned to absolute crap for the weekend, so it's a good time to work inside, flush the cooling system and heater core, and finally install the electric water pump that has been sitting around all month. I need a source of switched power for the relay that will control power to the pump. I deleted the air pump long ago, but the connector is still there. Is there a wire in that mess that is live when the ignition key is in the "run" position? The connector is in the perfect location to tap it for the relay.

If not the air pump connector, what would be your choice for a convenient source that could be tapped?

There are switched circuits in the under hood fuse panel.

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There are switched circuits in the under hood fuse panel.

Yep, there they are.  But, what I was hoping for was a particular wire for switched power outside the panel box that could be spliced into as a source to send to the signal side of the pump relay.  Any suggestions, or is this not a good idea?

Completed the prune juice, Exlax, and castor oil flush of the cooling system, removed and gutted the water pump housing, polished the housing exterior, installed the Meziere electric pump, and put it all back together, and torqued everything to spec. I wired the pump directly to the battery for now, just to test the system while I'm waiting on the proper 30A continuous duty relay and wiring harness from Meziere. Replaced all the old hoses.

(Note: the universal cut-to-fit hoses should be labeled as cut-to-sh*t, because that's what you'll have left once you try to fit it without rubbing against the front swaybar. Just skip that step and pay the price for the correct AC/Delco part....too soon old, too late wise.)

Jeeze, but there's a lot more room on the front of the engine now. You can even see what the optispark unit looks like without all of that other stuff in the way.

Replaced the thermostat gasket, but kept the GM thermostat because it works perfectly. New antifreeze (Prestone), 50:50 with distilled water (free at my place of work).

Fired it up, let it idle in the driveway under close supervision, and then drove 50 miles in tight circles near home in case of difficulty. Holds pressure and the temperature gauge is steady as a rock, and no leaks. Heater core is obviously working well. It's almost a shame to keep it inside the garage all winter. The operation was a success.

All I need now is that advice on where to pick up a switched power wire for the signal side of the pump relay.

Use circuit 3 air pump if you've deleted/disconnected it. Just use a fuse tap.

Cool. I had to look up a "fuse tap" under Google Images to see what it was. I had already thought of making such a device out of a spare fuse or two spade connectors soldered together. Dang.... someone stole my idea and put a pigtail wire on it to boot.

Thanks for your help, and continued patience with my naive questions.

Whoops! Circuit 3 (air pump) has constant power. That won't do. Would there be a problem in tapping into Circuit 6 (injectors) to run the relay? Would the added load to the signal side of the relay cause any issues?

Go to innovative wiring and get their instructions for the water pump harness they sell if you want pictures. There's a key on source on terminal 86 of the air pump relay that you can tap into and run to your own relay. I just did this when I installed my electric water pump.

On the 91-93 cars, most of the key on in bulb test, start and run are red with a black trace, or black with a red trace. I used a number of them to power assorted relays on my 454 install. The color code may be the same. Check your FSM for them. There is a wire to the vapor recovery canister that is the correct color. You can check it by turning the key on and off.