How do you guys wire electric fuel pumps? Back in the day, I would just run a wire from the fuse box to the pump at the rear and ground the pump to the frame. I haven't used an electric pump in many years but am going to now. Is there any real reason to use a system with a relay? If so, how do you wire a relay system and what parts do you use?

mostly a load issue on whatever is keying on the pump.
And lets you minimize high amp loads to the old wiring.

Personally I ran a power lead to a fused distribution block to the rear of the car.
Ran the relay from back there, put it all behind the back seat.
Ran the hot and ground through a body plug and ran the wiring to the pump.
I ran a ground distribution block to the back seat as well, all going to the battery through some big bulkhead connectors in the firewall.

Ran a single key on hot to the relay and hid it all along the sides under the trim. Can't see it unless you pull the back seat.
Going to be a pain if I blow a fuse, but I got bigger problems if I eat a 40 amp fuse.

Anybody else?

i run a aeromotive A1000 electric pump with a barry grant 2 speed relay box.
on the low setting i have only 50% of voltage to the pump for low load driving. when i want to step on it i flip the switch to high and get 100% of the voltage to the pump.
has worked trouble free feeding my 572 hemi for 50,000+ miles over the last 10 years.

http://www.jegs.com/i/Barry+Grant/132/180300/10002/-1

I ran mine to battery power at the fuse box with an inline fuse and toggle switch under the dash.

It depends on the pump and electrical load. If its a smaller carb pump drawing 5-10 amps direct connection to a keyed power source can work. If its a big pump with a lot of load, you need #10 wire through a relay to a good power source like the battery or fender relay. The connection should include a breaker or fuse.

Even with a small pump I think the relay is a good idea. It keeps a continuous added load off the key switch... which it was never designed for in the first place.

I've used a clean chassis ground for (-) with a big pump. No grounding problems.

I run mine on a relay with the ground going through an oil pressure switch so it stops if the engine stops running. That way, in an accident, you don't pump a tank of gas all over the pavement and then Just part of my occupational thinking, sorry.

What kind of relay do you use? Anybody got a schematic?

If I go old school and just run a hot wire to the pump, what size wire is needed?

Here's mine, with a oil pressure safety switch and prime button.

Besides using a relay, I use a 30 amp circuit breaker to feed the B+ from the battery to the relay (pin 30) instead of a fuse.