Been planning on trying this for sometime, finally got around to it tonight, so here it goes. I have a '91 B-13 SE-R with a Walbro 255, and also a trunk mounted battery. I used a 30 amp relay and harness from an off-road light kit, which had 12 guage wiring. I used what I believe is a ignition coil connector, (factory B-13, looks like 14 guage wire) that was cut from a engine harness. I soldered the new connector to the harness that was attached to the relay. The new connector fits the factory connector on the fuel tank perfectly, even locks in place. Power for the relay was taken directly from the battery, factory fuel pump wiring triggers the relay. All data provided by an OTC 300 digital multimeter with 200 amp current clamp. Battery voltage taken at battery,(duh!) and the pump voltage was taken by backprobing FP connector at tank. Fuel pressure is at idle, vacuum connected.
Battery Voltage Car off, ignition on: 12.7v
Fuel Pump Voltage-Prime: 10.29v @ 7.7 amp draw
Battery Voltage Run:13.9v
Fuel Pump Voltage-Run: 12.08v @ 6.9 amp draw
Fuel Pressure: 48 psi
Battery Voltage Car off, ignition on: 12.5v
Fuel pump Voltage-Prime: 12.02v @ 7.0 amp draw
Battery Voltage Run: 14.1v
Fuel pump voltage-Run: 14.0v @ 7.0 amp draw
Fuel pressure: 56 psi
Not bad for about 45 minutes of work, I would imagine it helps more for those with trunk mounted batteries, because the power wire to the pump is only about 1 foot long. Anyways that's my $.02.