Ford Motorsport Multiport EFI Engine Management Harness.

This manual is useful for any 5.0 EFI conversions.

Download the Ford Motorsport EFI Wiring Manual.

or view individual pages:

1 – table of contents, intro, overview
2 – component list
3 – component list, general installation instructions
4 – engine (injector) harness wire colors & connections
5 – engine (inj.) harness connection locations
6 – main & hego (o2) harness wire colors & connections
7 – main harness connection locations
8 – o2 harness connection locations
9 – tools, sensors & relays, engine (inj.) harness install
10 – engine (inj.) harness install
11 – engine (inj.) harness install
12 – engine (inj.) harness install
13 – main harness install, firewall hole pattern
14 – main harness install, firewall hole pattern, eec mount
15 – main harness install, brown splice
16 – main harness install, green splice
17 – green & brown connector diagram
18 – main harness install, hego/o2 install
19 – main harness install, hego/o2 install
20 – cautions, notes, grounds
21 – fuel system
22 – vacuum diagram
23 – startup, troubleshooting
24 – troubleshooting, general info
25 – misc. parts list and numbers

green brown – color coded splicing guide for the green and brown connectors

In progress: manual retyped for legibility and non-image-based pages – pdf files.

4 Responses to “Ford Motorsport Multiport EFI Engine Management Harness.”

  1. Joe Martinez says:

    Hello, I am in desperate need of some guidance. I am not sure what gauges will work with this harness. I would like to connectect gauges to the 8 pin brown connector, any information you could provide would be greatly appreciated.

    1966 Mustang
    5.0 HO EFI

  2. Drivesa5 Drivesa5 says:

    Hi Joe. As far as I can tell, you should be able to use standard gauges like Autometers, etc. If you look here, all they do to install a custom dash is tap into existing wiring, nothing more. Hope that helps.

  3. mustang howie says:

    Love your site ! Great name, I think I have the sameailment.
    Currently I have a ’67 Mustang Convertible which I am turning into a restomod with help from an ’87 5.0 EFI HO,my wiring comes from an ’89 (which was advised for me to use) and I am using MassAir.
    I am really stuck do you know where the 8 pin-connector is on the harness ?
    What connects from the 8pin-connector to the harness as I don’t seem to have a port for this, do I need to swap out the harness ? Also is the inertia switch connector next to the 8pin connector ?

  4. Drivesa5 Drivesa5 says:

    Thanks, glad you like it. Sounds like a fun project.
    Check out pages 6 and 7 in the manual, follow the number and it will tell you which connector is where on the harness. Also look at “green brown.” Those are the two 8 pin connectors and what you need to splice in from your original wiring to them – I’m not sure which one you’re working with right now. Those are pretty much the only things you need to wire to get the new harness to work with what you have – the rest is just connections for sensors, etc. Obviously, it won’t plug right in to whatever is there. I recommend acquiring the mating connectors for both green and brown so you can wire them up to existing car wiring and then cleanly connect and disconnect your new harness as opposed to hard-wiring in the new connections. The inertia switch will connect to some pins on the green 8 pin connector as shown in the diagram, unless you want to bypass it. Hope that helps you some.

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