DeatschWerks Hardwire Kit for Fuel Pumps & Dual Pumps

DeatschWerks Universal Fuel Pump Hardwire Kit (Single Pump / Dual Pump)

A fuel pump's output depends on voltage. Give it less voltage and it spins slower and moves less fuel, and that matters most at full throttle when the engine needs the most. The factory wiring between your battery and the pump is long and thin. It runs through a relay, a few connectors, and sometimes the ECU. Every connector and every foot of thin wire costs some voltage. On a car that's more than ten years old, corroded terminals and tired grounds make it worse. It isn't unusual for a pump to get a volt or two less than the battery's putting out, and that's flow you've paid for but aren't getting.

This kit fixes that. A relay mounted near the battery feeds power straight to the pump through heavy-gauge wire, along with a dedicated ground wire. The factory pump circuit still turns the relay on and off, so the pump still only runs when it's supposed to. The difference is that it gets full battery voltage when it's running. It's the right move once you're making serious power, around 400 whp is the usual rule of thumb, or if you've upgraded to a bigger pump on an older car. On a healthy, stock-power car with fresh wiring, you probably won't see any difference.

How the Relay Works

A relay is a switch controlled by a small electrical signal. The factory pump wire, which used to power the pump directly, now just triggers the relay. That only takes a tiny amount of current. The relay then switches full battery power through the new heavy wire to the pump. Your car's safety logic stays the same. If the ECU shuts the pump off, after a crash or with the key off, the relay shuts it off too. The kit uses a 40-amp Bosch relay and a color-coded 4-lead socket, so it's easy to see which wire goes where.

Single or Dual Pump Kit?

The single-pump kit includes 15 feet each of 12-gauge SLX power and ground wire, one 40-amp Bosch relay, and a 25-amp blade fuse. It's sized for one high-flow pump. The dual-pump kit is for setups like a twin-pump hanger. It includes two 40-amp relays, two 30-amp fuses, two 15-foot power wires, and three 6-foot runs of 10-gauge ground wire, so each pump gets its own power and ground. It also comes with nylon split loom to protect the wiring along the body. Two pumps draw twice the current, so don't try to run both off the single-pump kit.

Install Notes

Put the fuse as close to the battery as you can. It protects the whole run of power wire, so it needs to be at the start of it. Route the wire away from exhaust heat and sharp edges, and use grommets anywhere it passes through metal. Make your ground connection to clean, bare metal, or run it straight back to the battery negative. A bad ground undoes most of what this kit is for. When you're done, check the voltage at the pump connector with the engine running. It should be very close to battery voltage.

One important check before you buy: some newer cars run the pump at variable speed through a fuel pump control module rather than just switching it on and off. Wiring a relay into one of those bypasses the speed control, so the pump runs at full speed all the time. On a returnless fuel system, that can push fuel pressure out of spec. If your car uses a pump control module, talk to your tuner before you install this kit.

Fitment

• Universal 12V fuel pump applications
• Single-pump kit: one fuel pump
• Dual-pump kit: two fuel pumps, each on its own relay and fuse
• Check your car first if it has a variable-speed fuel pump control module