1987 2.0 Ranger ditching the computer

I have an '87 Ranger 2.0, 5-speed. I got it cheap with a blown engine. I had a mildly built 2.3 already so I'm putting that motor in the truck. It looked cluttered under the hood so me in my infinite wisdom began unplugging and ripping out wiring, relays and stock computer on the pass. fender. The 2.0 had a duraspark module and distributor and the parts store listed the same part #s for a '76 Mustang so I thought, okay, no problem, I'll plug the module straight into the distributor which worked but.... my positive coil wire went through the computer and one of my alternator main feed wires. Uh oh. It has an internal regulator and that plug is on the driver's side and separate from the computer. There was a big yellow wire hooked to the solenoid that goes through a rubbery fuse and splits to two big yellow wires. Could that be my new alternator wires? Has anyone stripped out these computers and got the truck to run? I use mechanical gauges so I'm not concerned with that wiring. I just need to find the resistance wire that goes to coil positive and how to hook up the alternator. Everything under the plastic cover on the pass. fender is gone so I hope it wasn't anything too important. Any help would be greatly appreciated. I daily drive a stock '86 EFI 2.3 so I'm anxious for some more power.

1987 coil shouldn't need resistor so use that coil not duraspark coil

Should be a Red/green stripe wire from ignition switch to coils "+" terminal

Diagram here: http://www.therangerstation.com/tech_library/EDiagrams/files/Diagrams_StartIgnition83to88_2_3.JPG

Alternator hook up is pretty strait forward, it reads like you have a 2G or 3G alternator, so internal voltage regulator.
On the starter relay(inner fender) is the the Power Distribution Post for the whole vehicle, Battery Positive cable is connected to that post.
All vehicle power comes from that post
On the back of the alternator is the B+ stud, thats the output voltage of alternator, you need a good size wire and fusible link that connects B+ to the Power Post

Then there is the 3 wire connector on alternator, thats the voltage regulators wiring
There is a short white jumper wire that connects regulator to alternators internal fields, it must be in place and no frayed wires for good connection

And then a Yellow wire, it is connected either to Power post with 15amp fuse or fusible link, or.........you can use 15amp inline fuse and connect this to B+, it tells voltage regulator amp draw, so it can regulate output voltage, so a monitor, no voltage on yellow wire means no alternator output, so it must be hooked up
It reads like someone has connected B+ and the voltage regulators yellow wire together already from your description, they both run to the Power Post thru fusible link

Green wire, this turns alternator ON and OFF, it comes from the battery light in the dash, battery light gets 12v with key on, alternator is OFF so 0 volts, so Battery Light comes ON
When you start the engine the voltage regulator uses that 12v from Battery Lights green wire to start alternator generating voltage, startup voltage, once alternator starts generating voltage the green wire now has its own voltage so Battery Light Bulb has "12v" on both poles, so goes off.
If alternator should stop generating voltage then Battery light comes back on


If your dash has an AMP Gauge and not a Volt gauge then other wiring is needed but it is added to above wiring, not needed to make alternator work

The '87 2.0 came with the round canister coil, duraspark box and distributor. I have a spare tfi square coil from my '86 2.3 I could use though. I've heard something about the square coils being able to run off straight 12V but wasn't sure. The yellow to two yellow wire off the solenoid seems to be factory. It ran into the bolt on computer plug and one of the 475 wires in the plug came out to the long skinny alt plug. All the other alt wires are seperate on a different harness. I was under the impression the computer was only for the feedback Asain carb. The truck has a volt gauge but none of the gauges work on either of my Rangers, that's why I use the 3 mechanical gauge pods under the dash. If I can get the engine wiring straightened out on the '87 I might try to get its fuel gauge working, that would be nice.

Any coil can run on 12volts(except tractor 6v coils, lol)

The resistor lowered the 14+ VOLTS, down to 8 or 9volts, for longer coil life

Battery is 12volt, alternator provides up to 14.9volts engine running

Yes, the TFI coil can dissipate heat better so it is fine to run on 14+ volts

Odd setup for computer, no reason in the whole wide world for it to connect to alternator.
It will connect to Power Post(solenoid) but just like everything else in the truck that needs voltage hooks to that post, i.e. cab fuse panel and engine fuse box


I have seen electric Choke heaters hooked to alternator, this is so they only heat up while engine is running, not when key is on.

You were right. I finally got a chance to find the wiring diagram on All-Data at work and the small center wire for the long alt. plug goes to the computer for choke heater. I guess I can leave that wire out. The big black/orange wire and the white/black jumper to the regulator plug are still there on the driver's side. I got a chance to look at the yellow wires I cut out of the computer that came off the solenoid. It's a black wire first, then the splitter to the two yellow wires says 16ga fusible link. My question is can i use these two yellow wires as the B+ alt. wires? My '86 only has two black/orange wires on the alt. plug and two on the regulator plug, not three each like the '87. I'm still looking for the resistor wire for the coil+ and apparently the duraspark module itself needs less than 12V. Another question, is an inline resistor something I can see like the fusible link or is it just a special section of wire?

Here's the wires off the starter relay on the battery side.

Yes, looks like a Fusible link, then splits to two yellow wires

On this diagram: http://www.therangerstation.com/tech_library/EDiagrams/files/diagram_charging_1983to1985_1.JPG

It shows double yellow for Trailer wiring................, really can't get my head around that one, lol

Yeah, I found that trailer wire on my diagram. Odd since the truck isn't even wired for trailer lights at the back. I just left the choke heater wire off the alt. I'll have to wait and see if it charges with just the one black/orange wire. I ran into ignition problems now though. I thought it was going to work bypassing the computer and using the stock ignition. I have power to the coil and to the duraspark box but no fire at the plugs. I'll give it a few more days of tinkering before I give up and get an aftermarket ignition box. FYI a Pacesetter header will NOT fit my '87 Ranger without grinding a cutout in the top frame rail for the #3 tube. That's what I'm working on now. Then it's on to rigging up a throttle cable or rod for the 2100 Autolite carb.

It worked!! The truck is running with its stock distributor and duraspark box and without its computer or feedback carb. I just used the alternator wires I had that were in a separate harness on the driver's side and just left out the center wire for the choke heater and it's charging like normal, a little over 14v. The wire that goes to the S terminal on the solenoid went through the computer also so I had to figure that out. I mistakenly hooked up a wire to coil + that wasn't hot in START. Once I found the wire that was hot in START and RUN the truck fired up. All the wires for the coil, ignition box, gauges and the power to the relay in START mode only are all together in one rectangle shaped plug on the driver's side. Basically you just have to figure out where each wire winds up after the computer and run new wires to each. The plug looks basically identical to the plug on my '83 F150 so I probably could have used an engine harness from an older Ford. The backup lights go through the same plug and I still need to hook those up but everything else is working. It actually looks like there's some room under the hood now and I'd figure I pulled out a good 5 pounds of wires, relays and the computer so lighter is always better.

Good work