EFI conversion

ID89GT · Apr 6, 2011

Okay I am making my list of everything I need to swap my 1980 Mustang over to EFI. I want to keep the same dash, so here is what I am thinking.. I have an 89 computer harness with the injector harness and 02 sensor harness. Can I just get an 86 Mustang body harness, and the 89 harness will plug right in? Or do I need to do some major wire modifications to make this work? Thanks

ID89GT · Apr 8, 2011

No one has any ideas?

FoMoCo1969 · Apr 9, 2011

the body harness and engine harness are basically 2 diff. harneses. I put an 88 speed density 5.0L in my 69 mustang and kept my factory 69 body harness. basically all u need is a couple hot wires to ecm and a good ground, your fuel pump wire and o2 sensors and thats it.

larrym1961 · Apr 9, 2011

Good luck Nick! I have a GT40 intake if your interested?

bdazzgt · Apr 9, 2011

i wired it in my 84, i used a 90 harness basically your installation will vary with the harness you have 86, 87-88, 90, 91-93 are all different. then you get mass air vs speed density. remember the inertia switch all the relays tach ect. its tedious but so worth it

ID89GT · Apr 10, 2011

Did you keep the 84 body harness and just rewire the computer harness to make it work? And as for the GT40 intake I have a 351 so that won't work for me haha

2000xp8 · Apr 10, 2011

See if helm inc still has the wiring diagram for your car and the car your new harness is from.
Helm inc makes the real books for ford.
Worth every penny, i must have used them 200 times over my cars life.

Most recently is aided in my recent conversion, not sure i could have done it without them.

Don't get the online version, you need to have the book to thumb through it as you work.

Edit: Wow they do have it, and only $15, that's like $65 less than it was for the 03 cobra.
1980 Mustang/Capri Electrical & Vacuum Troubleshooting Manual - Helm Incorporated

Once you learn how to read it, you can source any wiring you need.

larrym1961 · Apr 10, 2011

ID89GT said:
Did you keep the 84 body harness and just rewire the computer harness to make it work? And as for the GT40 intake I have a 351 so that won't work for me haha

Well then, If you come rumbeling up next to me on the streets of CDA, I'll know you have a few more cubic inches than I do!

And beware of that burgandy and beige '96 F150 running around town, he's got a pretty wicked supercharged 331 under that hood!

ID89GT · Apr 10, 2011

Sweet deal, ill def be ordering the book then. Ya I've seen that truck a few times haha, that thing sounds mean

2000xp8 · Apr 10, 2011

ID89GT said:
Sweet deal, ill def be ordering the book then. Ya I've seen that truck a few times haha, that thing sounds mean

Might as well order the book for the year efi harness you are using too.

ID89GT · Apr 10, 2011

Good idea haha. So I will need the book for my 1980 and then also for the 1989 Mustang, correct?

2000xp8 · Apr 10, 2011

ID89GT said:
Good idea haha. So I will need the book for my 1980 and then also for the 1989 Mustang, correct?

Ya.
You won't be sorry though.
Study the book at night a little bit, takes a bit of getting used to, to read.

When i converted to my 03 cobra engine, i took all the relevant circuits in the whole book and highlighted them different colors so i could just thumb through and find the important stuff.

There is plenty of info on the internet about the mechanicals of an engine, but when it comes to wiring, there's very little.

ID89GT · Apr 11, 2011

Haha I hear ya on that one, wiring diagrams are hard to come by online

venom97 · Apr 11, 2011

Ok guys,maybe you can help me here. My wifes cousin just put a fuel injected 302 out of a grand marquee(sp?) in his 83 capri and he can't get the thing to start. Cranks over,fuel pump kicks on(newer fi pump),and is getting spark. I went over and looked and he's getting 12 volt to the coil but when cranking it drops to around 4 volts. Car cranks good,good battery,what could we be missing? Even with ether it won't even fire. Any help would be greatly appreciated!

jrichker · Apr 12, 2011

PM me your email address and I will send you a complete Ford Factory 89 Mustang electrical diagram set. The zip file is 2.5 MB and is too big to fit through Stangnet's email gateway.

89 Mustang wiring diagrams zip package–

They are in a zip file format to reduce the size of the package. You’ll need WinZip or other Windows archive tool to extract them from the zip file. See MajorGeeks.com - Download Freeware and Shareware Computer Utilities. - Download Freeware and Shareware Computer Utilities for a free download.

You will need the Adobe Acrobat viewer which is also a free download – Adobe - Adobe Reader download - All versions - Adobe Reader download - All versions

EFI conversion

ID89GT

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FoMoCo1969

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larrym1961

bdazzgt

I had to jerk off the cable to get it to stop.

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2000xp8

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ID89GT

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ID89GT

2000xp8

ID89GT

venom97

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jrichker

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EFI conversion

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I had to jerk off the cable to get it to stop.

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