New engine about to go in

[exukpaul]

Hey guys. Bought my factory five a couple of weeks ago now. I've been told by a member on here that it is a mk2.
So, i bought it with no engine or trans and am about to put a 351w in it. This is all new to me, I've put 2 or 3 engines into cars before but it was just like for like. I'm feeling a little overwhelmed with the wiring thing. I haven't a clue what was in it before so there is a little left over wiring. Didn't know if i need to pull it out or what. I'm guessing the connector hanging by the radiator is for the alternator ?
The light brown plug i don't have a clue about nor the green one. Any feedback would be very much appreciated.
Thanks 195678195679195680

[Rdone585]

You will probably have to trace the wires back to their source to find out what they are for. If you can trace them to the fuse panel that can give you a clue. Do you know if the previous engine was carbureted or EFI? If you find a computer board it was probably EFI. If you find a MSD box or a generic version of one, it was carbureted. Can you find a coil? Are there any signs of a fuel pump (options are in tank, external electric, or mechanical but these are mounted to the front of the engine). Some of those wires should go to gages, find out what goes to what and that's a start. The flat cable with no insulation is the ground strap to the engine block. Heavy gage (i.e. thick) wires are typically starter or battery.

[exukpaul]

Thanks for the reply. One of the guys on here did mention that it looked like it had a 5.0 efi previously when I posted an introduction. I did look under dash and couldn't for the life of me find an ecm or msd box. It did have one of those kinda square looking black coils under tge hood which i removed. I've tried to look above fuel tank and it looks like a bunch of wires going to what i would think is an in-tank pump.

[David Williamson]

the square black coil and the starter solenoid are Mustang parts so likely the car had a donor Mustang engine and the wiring is probably from the donor car. you might find it easier to take it out and start again with a new engine and ignition wiring system.
David W

[exukpaul]

Thanks David. What i can't get my head around is if it was an efi, i can't see any evidence of an ecm, a disconnected plug or anything. Like i said, looks like it has an in-tank fuel pump. I kinda feel a little limited with my electrical knowledge as to completely re-wiring everything. It may be the way to go though i guess

[Rdone585]

If it has an in-tank pump it's most likely that the previous engine was EFI. Check to see if there is an inspection plate in the trunk. Some put them in so you don't have to remove the tank to service the pump. As mentioned, if you're up to the task, rewiring could be the best solution long term. That way you at least know what you have. It's possible you could leave some of the wiring if it's in good condition, for example the lights, and turn signals.

[exukpaul]

If it has an in-tank pump it's most likely that the previous engine was EFI. Check to see if there is an inspection plate in the trunk. Some put them in so you don't have to remove the tank to service the pump. As mentioned, if you're up to the task, rewiring could be the best solution long term. That way you at least know what you have. It's possible you could leave some of the wiring if it's in good condition, for example the lights, and turn signals.

Gotcha. Maybe i will have to go that route. There is a flap/door in the trunk but its in the middle and has the battery in there

[Jeff Kleiner]

...One of the guys on here did mention that it looked like it had a 5.0 efi previously when I posted an introduction ...

I think I'm that guy ;) As I said then you have vestiges of an EFI Mustang harness. The brown plug is #31, green one is #39. Wires in those plugs relate to the Ford EEC-IV EFI (TFI module, O2 sensors, etc.)

https://www.veryuseful.com/mustang/tech/engine/images/mustangMainHarness.gif

Hard to say what may or may not have been stripped from the original harness, if anything. Back in the early days (Mk1 and Mk2 especially) it wasn't uncommon for builders to diet out unused/unneeded circuits or even leave the entire harness intact and then just stuff the unnecessary segments behind the dash and firewall. The big question for you is what are your plans for the new engine. Carb? Fuel injected? If injected what kind? If you're going carb virtually none of the old EFI wiring will be used, nor will the in tank electric pump (unless you step down the pressure). If aftermarket injection such as a Snyper is used you just need to give it power and fuel in which case the in tank pump can come into play. Really hard to give you much more until we know where you're heading with the new engine.

Jeff

[exukpaul]

Thanks Jeff and hello once again !
Yea, i was thinking just going holley carb and msd ready to run distributor. I have thought about the holley sniper but if i did go that route, its minimal wiring anyway right. I did install a sniper last year on my ski boat because the ecm went bad and they don't make them anymore. It was pretty easy to install

[egchewy79]

As Jeff mentioned, with a carb, you can use the in-tank pump but would need a pressure regulator to bring it down to 5-7psi. With EFI (Sniper, FiTech), you'd need a return fuel line as well.

[exukpaul]

Maybe I'll just lose the in-tank pump unless i go sniper.
So if i completely re-wire is something like this ok ?
https://www.speedwaymotors.com/22-Circuit-Universal-Automotive-Aftermarket-Wiring-Harness-Kit,229874.html

[Jeff Kleiner]

Maybe I'll just lose the in-tank pump unless i go sniper.
So if i completely re-wire is something like this ok ?
https://www.speedwaymotors.com/22-Circuit-Universal-Automotive-Aftermarket-Wiring-Harness-Kit,229874.html

That's configured for a GM steering column so would require some amount of modification. If you want to hit the "East Button" do this:

https://www.ronfrancis.com/product/248

It's as close to plug & play as you're going to get.

Jeff

[exukpaul]

Ok. Thanks. I'll look into that.

[john42]

Thanks Jeff and hello once again !
Yea, i was thinking just going holley carb and msd ready to run distributor. I have thought about the holley sniper but if i did go that route, its minimal wiring anyway right. I did install a sniper last year on my ski boat because the ecm went bad and they don't make them anymore. It was pretty easy to install

I (with help) just did a motor swap from a 1990s 5.0 EFI to a new Boss 347 with a Sniper 2. The Sniper 2 wiring was a cake walk. It was very nice to remove the old EFI rats nest.

[exukpaul]

I (with help) just did a motor swap from a 1990s 5.0 EFI to a new Boss 347 with a Sniper 2. The Sniper 2 wiring was a cake walk. It was very nice to remove the old EFI rats nest.

Yea, thats why i thought I'd go old school with the carb but i know the sniper is a pretty simple installation and minimal wiring etc

[phileas_fogg]

Another advantage to using the Ron Francis harness Kleiner recommends is that there are TONS of builders who have that harness...carb guys, EFI guys, probably even some donor engine guys. It'll make your future trouble shooting sooooo much easier having a network of helpers at your fingertips.


John

[bobl]

I did a complete rewire on a MK 1 Roadster that had the old ford harness. I used a Painless universal harness and it was pretty straight forward (if you have some electrical knowledge), not much more difficult than the Ron Francis harness. I could not believe how much old wire we pulled out of that car.

[exukpaul]

I'll look into that too then.
Thanks for the info my friends. Something for me to get my teeth into.
Lol, I thought I got a deal with the car buying it without an engine and tranny but there are so many things I'm needing that I didn't think of haha

[BUDFIVE]

Some more thoughts on the in-tank fuel pump. An in-tank fuel pump gives you flexibility. It is
becoming a popular choice even with carbs, especially with a bypass style (with return) regulator, like
Holley 12-887 (4.5-9psi). There is an identical footprint regulator 12-886 with a fuel injection pressure range, (15-60psi). I believe they make a regulator with both springs so both adjustment ranges but I don’t have the part #.. The point is you can build the system to support both fuel injection and carbs with a simple bolt in regulator swap. If you use an in-tank pump with a carb, I suggest you watch the video on ProM Racings site which shows the importance of a correctly sized return line (equal to feed line). You see a lot of guys on the forum using the ProM fuel pump hanger for its 3/8 (6AN) feed and return connections. Holley has some good videos on why an EFI in-tank pump with bypass regulator is the best solution, even for a carb—the fuel is constantly circulated and stays cool, avoiding vapor lock, etc.
https://www.holley.com/products/fuel_systems/fuel_pumps_regulators_and_filters/regulators/
The other vendors offer similar regulators-I’m just more familiar with Holley.