I have recently done a V6 to V8 swap on a 91 RS
Now I'm in process of wiring up my fuel pump to
run when the ignition is turned on. It feeds into a Mallory 3-port regulator then to a 625 Road demon. I know the fuel pump relays are on the drivers side firewall, and the wire I need is a gray wire on one of the relays. My question is what is the best way to wire up the fuel pump to kick
on when I turn the key?

 

What are you using for a fuel pump? the stocker?
if so you shouldn't have to mess with it.

wiring up the fuel pump like that is easy tho. just find the fuel pump relay. it'll have at least 4 teminals, 2 with a smaller spade connectors (for the switched leads) than the other 2 or 3 (the actual pump leads). They're labeled with numbers, but I forget which is which. There should be a diagram on top of the relay too. Use a test light to find a source (any source) that is hot only when the key is on. Run that to one switch terminal, and ground the other.

 

What happens is, when I turn the ignition key on to start the car. The fuel pump kicks on for a couple seconds, then shuts off. I believe this happens because I'm not using the ECM?

Thanks for your help Jester

 

Oh, and yes it is the stock fuel pump.

 

Yeah it does that. Safety feature I suppose. So long as it runs when the engine runs, (which it should) it should be fine.

 

That is the fuel pump priming. Since you still have the relay hooked up (and probably the oil pressure/ fuel pump switch), the pump will still prime before start-up. I didn't think that circuit would work without the ECM (at least according to the diagrams I have), but I guess it does. Don't worry, it's supposed to do that, and it should have done so before you swapped the carb.
Hey, I'm thinking of buying a rd. demon, too. Have you fired your car up yet? How's the carb working out?

 

I'm planning on wiring up the fuel pump this weekend. So I'll let you know how the demon runs.
Up close it seems to be build very stout, When comparing it to my Q-jet. It looks very similar to a Holley. A cool feature that came on the Road Demon is on the float bowls where you adjust the floats. You can into the float bowl to see where the float is sitting. I thought it was cool!

 

Hey, that is pretty cool. Let us know how it goes.

 

you realize you can get clear sight plugs for Holley for like $5 right?

 

I did the swap...yes you have to bypass the relay so the pump will continue to run....computer wont let it work....I bypassed mine between the rear seats . There is a relay there. Real easy to do.