Holley Electric Fuel Pump Relay Wiring?

[cletus]

Dear Hive Mind -

Here is another question about adding an electric fuel pump. The idea is to wire in a relay to switched power, I currently have an MSD 6A box wired in place of the original ballast resistor and factory ignition box, am I going to cause any problems by pulling switched power to the relay that will then run the fuel pump off of the same switched power (original ignition circuit) that is hooked up to the MSD, or do I need to pull it from something else?

Any help with this is appreciated, thanks in advance.
- Steve

 

[crackedback]

If you run a relay at the fuel pump, that wire supplying a trigger should be OK. Terminal 85 or 86 on the relay

You DO NOT want to power the pump from that wire, terminal 30 on the relay. That terminal should have a fused wire from the battery/alternator to power the fuel pump.

If you want something put together using a tyco/bosch relay, let me know. I can put something together for very reasonable cost.

 

[Mopar Tim]

I always use the Hot wire to the oil pressure light. It is hot all the time, it just goes on, the light, when it is grounded thru the oi pressure sender. It will always have Batt+ there. IMO it is the perfect place to get the trigger current for a fuel pump relay.

 

[cletus]

That is exactly what I was looking at doing, thanks a bunch for the info. I don't need anything made up, I do appreciate the offer though.

I already have a relay and plenty of wire and connectors to do the job and I am pretty well versed in repairing and replacing existing wiring, I just wanted to double check to make sure I wasn't going to cause any problems running it this way. I already have the body wiring to the back of the car removed, the plan is to strip the tape off of it to inspect and repair anything that needs it, and then to re-wrap it with the additional power wire for the pump so it's clean and run the negative from the pump straight to ground at the frame where it's mounted. I will probably mount the relay where the ballast resistor used to be, I believe that's far enough from the exhaust that heat won't be an issue.

Thank you!
:cheers:

 

[crackedback]

Cool,

I usually like to mount relays fairly close to item it's powering. Makes it easier to diagnose if something goes wrong.

Sounds like you have a good handle on this. Good luck with your wiring.

 

[cletus]

Crackedback - I don't think diagnosing issues in that system will be terrible either way, there isn't much to it.

Tim - That's a great idea, I hadn't even thought of it, I don't have the original sending unit in the car anyway as I have an aftermarket gauge. So then I could tie in to the low amp side of the relay right off the gauge cluster and keep the relay behind the dash, less wiring through the firewall. I like it.

Thanks guys!

 

[cletus]

That reminds me, on a side note, I have a wiring diagram printed out I got on the internet from an old service manual hanging on my garage wall, I'm going to have to start making some changes to that to show what I actually have in the car where it doesn't match the original.