Converting '85 Coupe to EFI 5.0, what all am I gonna have to

[mustangsandcamaros]

Hey, I have a '85 coupe that was an ex 4cyl 4 speed car, I have started to convert it to full EFI 5.0. I have already ran my wires for the fuel pump in the tank and the inertia switch, now I need to know how and where I am going to hook them up to. I am using a '88 GT car for some of the wiring. I am also swapping out the whole engine compartment harness with one from a '86 so I get the battery and alternator where they need to be. Will I need to change the dash harness too or can I just add or splice in wires where needed to power the EEC and the fuel pump relays? Any help is appreciated, I am sure some of you have done this swap before. I have the connector on the passenger side under the dash that is green, and has a small black wire, a big orange/black stripe wire and a blue/gree stripe wire, will I use any of those to connect to the EFi harness inside the car? I know I gotta have a key-on hot for the O2 sensors, but it all gets overwhelming a little. Thanks guys.

Clint

[85 Notchback]

I would have just said strip the 88 GT of the whole wiring harness front to back, take the gas tank, and call it a day..

[mustangsandcamaros]

Dont want the newer dash or headlights, plus this is a non-air car and want it to be close as original as possible. Goal is for it to look like Ford made it back in '85 with multiport EFI and not too many cut and spliced wires.

Clint

[mimustang]

I recently completed an EFI Mass-air swap on my 85. It was a little different than yours as my car started as a 302. Basically, you'll need:

Fuel - I'm not sure of line size/pump size on the setup you have now, but I ran all new lines (-8 AN for the feed and -6 for the return). There are spring lock connectors on the factory fuel rails - you can either search for adapters or move to a set of aftermarkets. I went the adapter route but plan to switch to 1/2" aluminum's at some point in the future.

Hardware - Look for a complete EFI take off. The things that will nickle and dime you are the sensors/small parts. Find a complete take off that includes the lower intake, upper, fuel rails, injectors, throttle body and spacer, coolant tubes, egr, vacuum tree, throttle cable bracket. You'll also need a throttle cable from an 86-93 302.

Speed Density (SD) vs. Mass air (MA) - you'll need to choose between the two. If you have significant mods (cam, heads) you'd be best going mass air, the computer adapts to changes better. If you have a pretty stock motor, speed density will actually give you better performance and is easier to get running. 86-88 cars ran speed density and 89-93 ran mass-air. 88 California cars ran mass air I believe. Pick a direction and find an appropriate computer. If you run MA, you'll need a mass air meter too. Don't forget the plumbing too. Air intake ducting is specific to SD vs. MA.

Wiring - You'll need an injector harness. This harness is the same for both speed density and mass air cars. Next you'll need a computer harness - this plugs into the injector harness and the computer, making it SD or MA dependant. There are a couple connectors that you'll need to splice/cut up to get power and connectivity to the computer. These are both on the computer (main) harness, not the injector harness.

Look for the brown connector - should be located behind the drivers strut tower in the engine compartment. You need to set up the following:
Red/light blue - 12 volt crank only
White/purple - 12 volt crank only
Red/green - 12 volt crank and run
White/red - goes to your oil pressure dash gauge
Tan/yellow - Tach
Green/Purple and Purple yellow are for a neutral safety switch - open circut allows starting. Should run to your clutch switch and neutral switch on a T-5 (or whatever). Leave open if you have an automatic.

Almost there - look for the green connector, it will be located inside the car right by the computer connection. You need to set up the following:
Gray/yellow - 12 volt run only
Purple - AC idle control - 12 volt when air is on to increase idle speed
Dark Green/Yellow - Fuel pump control - to inertia switch then to pump (really should run this through a relay)
Pink/orange - Speed sensor negative/ground
Green/black - Speed sensor positive
Pink/green - Check engine light

That's about it. Make good connections (that means solder and heat shrink, not crimps) and get a GOOD body ground for your computer. Factory gauges should work fine (4 cyl tach might be an issue, some have a switch 4/6/8 - check yours out, otherwise find a v8 tach and swap it out).

Everything is available for a good factory fit since the 86's came with the same setup.

[mustangsandcamaros]

Thanks, anyone done this to a factory 4 cyl car like I am doing? Do you have to have the speed sensor wires hooked up for the ECU to operate right? Seems like I have left them unhooked on the tranny before with no problems.

Clint

[v8only]

wow, this is pretty comprehensive, archive nomination!!!

i'll be doing this soon, and you have to excuse my utmost ignorance on this subject, electronics have never been my cup of tea.

some you say 12 volt crank, 12 volt crank only, what are you talking about?? just hook up to a power source?

12 volt run only?

speed sensor negative ground? so just ground out that cable.

speed sensor positive? hook that up to what?

great post!!

[Capri50]

Thanks, anyone done this to a factory 4 cyl car like I am doing? Do you have to have the speed sensor wires hooked up for the ECU to operate right? Seems like I have left them unhooked on the tranny before with no problems.

Clint

you do not need the speed sensor hooked up. My EFI conversion is coming on 6 years now without an issue. Some have claimed it will caused stalling on deceleration, but i've never had this problem.

Much of this information is well documented in the Motorsport harness install manual from ford. I will have to scan it one of these nights and post them up. The wiring is very easy to follow.


ps. don't forget when swapping over to an 86-93 tank, you will need an 86 specific fuel sender. This was the first year of EFI, last year of our 79-86 dash. So only the 86 sender will work properly. They are still available NOS for about $60 or so.

pps. also the yellow/gray wire should be hooked in the thick yellow/gray ignition wire under the steering column. This helps power the high-draw heated 02 sensors to get them up to temp. Running on a thin guage wire can pop fuses/melt wires, etc.

[v8only]

great info, maybe if you get a chance, you could scan that and post it here?? this swap isn't sounding so bad after all.

[mfpmax]

Archive nomination indeed, thats what i'd post if I had a clue :D Instead of some of the suggested using the newer dash.

[mustangsandcamaros]

Thanks again, I pretty much think I have it all figured out now, but didnt know that bout the '86 only sending unit, that stinks, oh well....I am pretty good with wiring, the main thing is I dont have the engine compartmet harness yet so I dont have power yet, so I cant check where I have it or dont have it at ya know what I mean? But as far as all the power for the EEC relay and all that goes it basically all works off the engine compartent harness and plugs up to the EFI harness right?

[mfpmax]

Yes, according to my old Turbo 4 wiring, My EEC relay gets a ON signal from the coil and I have a direct 12v line to the battery. At least I think I do. I may have 12v taped in somewhere else.

And yeah, as mentioned on Corral(at least I think I did), the fuel sender thing sucks, you'd have to get a EFI/CFI sender or just do what I'm gonna have to do and use the EFI sender, with a aftermarket fuel gauge.

[mustangsandcamaros]

Yeah, now I remember you from there, thanks fro the help ma man!! I think once I have the harness I will be able to do it no problem, just wanted to get a heads-up to things like the fuel gauge not working with newer senders. I could just swap in the 140mph 87-89 gauge cluster in the 4-eye dash...think it could be done without looking like complete butt??

Bueller......

Bueller......

[mfpmax]

It'd look out of place and I don't think it'd fit, but sicne I think you have it, see so...but if it requires more work...forget it.

Someone on another forum put in a newer tank and did the dash and regrets doing it because it was so much work. The Autometer Fuel gauge is about $30-40 I think and comes in the correct ohm reading for the 87-93 senders.

[mustangsandcamaros]

Yeah I know I was just thinking gay for a moment I guess...I may try an do a custom gauge cluster as well and end up using the autometer style gauges too.

[Cobra Jet]

I've got a question about the "86 only" fuel sender - as I have heard this multiple times on a few sites, and even when discussing locally, etc...

Can someone list the actual differences or WHY if doin an EFI conversion in any 1985- prior Mustang that it is so pertinent in having to use an 86 only EFI fuel tank pump unit?

is it the connection that is different?

the float?

the actual wiring once the pump is installed?

the diameter of the units?

???

Just very curious to know the exact reasoning...?

Also - woudl ANY 1986 fuel sender/in tank unit work, OR is it V8 (5.0 specific)? I guess with that statement in mind now, if it is only to be from a 5.0 V8 - is the sender or unit specific to the Mustang ONLY, o can it be grabbed from any 5.0 V8 produced in 1986 by Ford/Mercury/Lincoln??

I just can't see Ford producing such an item for a SINGLE line of vehicles in 1986 - it's not cost effective... My thinking is, this unit is or was used in other Ford vehicles too. ?

Anyone?

Maybe there should be a separate thread on just this subject?

[mfpmax]

The 86 only deal probably has to do with it being similar to the later models, but having the correct resistance to work with the cluster.

As LTDScott I think pointed out, I think the SVOs had a combination system with the pump and sender in the same area...I haven't confirmed this.

I'd like to ASSUME that the CFI V6s would also be a correct source for the sender, but I have yet to confirm this.

But pretty much 86 is an almost sure fire sender because both the Auto and manuals were EFI, while 85 had the carb and CFI. At least for the V8s. Not sure on the V6 CFI cars. And for certain the 4 bangers use carb senders(I have an 85 and 86 4 banger).

This seems to be one of the wonderful mysteries of Ford.

[mustangsandcamaros]

Also on the fuel sender deal: Will the fuel gauge work at all in the 4 eye cars with the use of the 87- sender? I mean if it wil work but read somewhat off I can deal with that till I can find a electric in-tank setup from another 4-eye car. Is the tank any different as I will be using the tank from a '93 LX 4 cyl car or maybe the one out of the '88 GT, do you know if they have the same fuel pumps as the 5.0 cars? I think they do if I am not mistakin.

[mfpmax]

It reads totally backwards apparently. I've never let my tank go over half a tank though. So its read empty since i installed it.

The fuel pump is the same from 86-93. Thank fits just fine. Only difference is the sender unit is in the middle instead of near the filler neck.

[Stangracing]

86 Coupe org V6 car
My brothers-in-laws coupe (6cyl) doing V8 swap carb. he pulled the wiring harness out and just cut the wires at the end......I can hook up the yellow wire and it gives power to fusebox and everything in car even taillights etc.

the only thing we need is headlights turnsig.

Look at the mess of wires and let me know if anyone has an idea how to hook up and diagrams would be great

http://stangracing.com/dustyWires.JPG

Any help would be great[[/img]

[Stangracing]

http://stangracing.com/dustyWires.JPG%20

[Stangracing]

anyone???

[foureyedfool]

I did the exact same swap last year using a 86lx non ac car .I used a wrecked 86 gt for my harnesses and a wrecked 88 gt for the drivetrain and brakes.Everything was just a plug an play ordeal but I did have to swap the dash harness from the 86 gt to the 4 cyl car for everything to just plug in with no splicing.Its not that bad if you have a donor car .I cant imagine doing it any other way.

[mustangsandcamaros]

Yeah foureyedfool, I just got a '86 Gt vert from my brother with everything still on it. I am going to use most of the wiring, but I think I will leave the dash harness in the '85 since it is simplier. I think I iwll just have to splice in a few wires to get it all right. Do you have a idea which ones? There is one that comes off the EFI harness from the '86 GT that is all by itself black/white line and seems to plug into the harness for the power locks or windows on the car. Do oyu know what this wire is for? Its comes out of the harness by the ECU inside the car by the fuel pump relay wiring.

Clint

[foureyedfool]

save yourself alot of time and frustration and just swap the dash harnesses.Trust me it isnt that bad.

[mustangsandcamaros]

I am not worried about the actual swap, its having less wires that I like. I will try it and see, if it doesnt work I will swap dash harness as well.

Clint

[Matt00gt]

I have to chime in here because I recently installed a 5.0 out of a 1992 into an 1985 former V6.

It has been awhile since I did the wiring but I didn't need to splice anything if I recall. I found the headlight harness for a 1986 5.0 and plugged it in under the sterering column. I then found a 1986 ECU harness and plugged that into the headlight harness.

Now when we installed the motor I was thinking abouth running wires to the fuel pump and inertia switch but my father who installed the tank said that he plugged everything right in. I didn't understand since the V6 had an external fuel pump that I removed and the conector for it was under the car near the rear seat.

Well, when we were ready to fire up the motor I had my doubts about everything working because of this fuel pump issue. Sure enough when we plugged in the computer and turned the key the fuel pump kicked in. The car has been running for several months now and reading this still makes me wonder why we didn't need to do any splicing. I have the green connector near the ECU just sitting there not connected to anything. I am at a loss how everything worked.

[mfpmax]

Some of the CFI cars(or all) had two pumps, just like the SVO. A helper pump on the frame and an in-tank pump.

[Matt00gt]

Ahh Ha. That explains it!

I was wondering how the hell everything went so easily.

[mfpmax]

Makes me wish my car would've been a V6. Cause on the 4 bangers, we have carbs and the fuel tanks aren't EFI compatible so we have to swap our tanks.