Subaru Fuel Pump Wiring System Upgrades

Subaru Fuel Pump Wiring System Upgrades

Sep 8, '21
In this blog post we talk about our suggestions for how to best upgrade the fuel system of a Subaru from a wiring perspective. For all fuel setups we make the wiring simple with our Fuel Pump Controller Hardwire Kit so you get maximum power to the pump while leaving the Fuel Pump Controller (FPC) in place to regulate how hard the pump works. 
Here is our owner Brian giving a little background on the fuel pump wiring, how it came about and why it needs to be addressed.


We wanted to supplement this with a few key ideas in regards to fuel pump wiring with our most up to date knowledge. The underlined headers are links to the specific articles in iWire University.

What Does a Fuel Pump Controller Do?

The fuel pump controller is there to regulate the ground side of the fuel pump (EJ platform) to run the pump at low, medium, and high speeds depending on how much fuel the engine needs. This is important to keep fuel pressures inline, fuel temperatures down, and for safety.

Basic Knowledge About Our Hardwire Kit and What It Does

The above post is some general background if you need a little more clarification on what the fuel pump hardwire is and why it's important.

  • Although other companies make "hardwire" kits what we are offering is very different because it is specifically tailored to your vehicle to be 100% plug and play as well as we have thought of all the potential failure points and addressed them. What we provide is a hardwire solution instead of a hardwire kit.
  • Our material selections are much higher grade than most others so it will handle whatever you can throw at it.

Upgraded Fuel Pump Controller Misconceptions Explained

This post gives a lot more detail of how we got to this point in regards to upgrading the fuel pump controller and is definitely worth a read. The key takeaways are

  • You do not need the upgrade fuel pump controller
  • The upgraded fuel pump controller is not a solution if you are running out of fuel
  • We do not recommend that you purchase a Walbro 525/Hellcat pump
  • If you need a 525LPH pump we recommend that you switch to 2 smaller fuel pumps to divide the work and give you more fuel

The Stud Bypass Kit is an Important Tool to Eliminate Fuel Pump Failures

  • The stock connector is not designed to handle the amount of current that is required for a large pump and will eventually overheat, melt, and then short out killing the pump and controller

Does the Hardwire Kit work with the 15+ WRX?

  • Unlike the EJ platform the FA (15+ WRX) models have a fuel pump controller that regulates the pump on the power side, not the ground side which makes a true hardwire impossible at this point.
  • We currently make a custom kit that removes all of the stock wiring from having to handle any load (work) so that if you increase the pump size the wiring will not be an issue.
  • Generally speaking we recommend a Radium 2 pump setup for this platform because it allows for a large increase in fuel without putting as much strain on the stock fuel pump controller and we can build a custom plug and play harness around it.

#FuelPumpController #FuelSystem

Tags: Fuel System