Classic Mustang Fuel Injection

This page is a bit older and will be updated soon with my installation of a MS3Pro Evo. But in the meantime, I’m leaving this information up for anyone who’s interested in swapping in a factory style EFI system.

The most popular EFI (electronic fuel-injection) swap for classis Mustangs is to take the complete setup off of an 89-95 5.0 Mustang.  Factory EFI on these models of Mustang (or Bronco, F150 and Crown Victoria systems) utilize a mass airflow system to meter and control fuel and injection, a system which is adaptable and can accommodate modifications.  Other options include Accel 7.0 DFI, the Holley Pro-Jection, and Edelbrock Pro-Flo EFI.  These aftermarket systems are all based on speed density system which is less responsive to changes, and often require tuning.  Fortunately these systems are still an improvement over carburetion.  Unfortunately, these systems start at over $1500, a pricey proposition.  An excellent discussion and comparison chart on the attributes of each system can be found here on

My first attempt at converting my ’67 to EFI was to utilize a Megasquirt “do-it-yourself” computer system along with an Accel 74302SR carb-style intake and a billet “4-barrel” throttle-body. Following a not-so-successful attempt at building the computer myself, I scrapped the project and decided to adapt a ’90 Mustang wiring harness to the car and use a factory-style system.

Following instructions on, I was able to wire the harness into the ’67 and have it actually start at the first crank of the key! One word of warning… while the instructions on the above website are good, they’re not for the faint of heart. Be prepared to spend a lot of time tracing wires and planning out your system. If you’re not comfortable soldering or doing electrical work, buy one of the pre-made harnesses. I ended up using the 4 relay setup shown on the site by buying a 4 relay module from Summit (Part # ARC-1440).  Additional changes included the inclusion of an MSD ignition box and future setup of a WOT relay for the AC (more to come on that).

Aftermarket parts I used for this swap:

Other than the above, you’ll need to source the following from a donor car or purchase new:

  • MAP Sensor
  • Distributor w/ TFI module
  • TPS Sensor
  • Relays for Main Power and Fuel Pump (and possibly more if you modify the harness)
  • Throttle Cable
  • Pedal for cable-style throttle (I used a ’70 Mustang pedal, didn’t require any modifications other than moving the location)
  • O2 sensors w/ bungs
  • VSS (Vehicle Speed Sensor)
  • Compatible Speedo Cable for VSS (see Ron Morris Performance)
  • Factory Inertia switch and connector

Highly Recommended Websites:

A no-tune dyno result:
Fuel Injection Dyno Chart

One thought on “Classic Mustang Fuel Injection

  1. Pingback: 2014 – A Year Behind the Wheel and Behind the Lens | Oversteer Garage

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