Carbureted LSX forum - Wiring help on fox carb swap

Ok guy i have a few problems id like to get fixed.

Car info is 88 fox coupe with a 08 stock longlblock 5.3. Has a th350 with art carr 3500 stall.

All power wire and ground wires are new, as well as Starter and Battery.
When trying to crank the car over most of the time all i get is one single click of the selonoid pushing the gear out but not cranking. And then every blue moon i get it to crank. Iv sanded the block were the starter bolts to as wells as all ground straps. Also ran an extra ground to the intake straight from the battery to the intake. A couple of times i have rotated the motor over by hand from the crank pulley and it either clicks o few times after i try to crank again or it turns over first try. Help me please lol

Second problem is it countinues to run after i turn the ignition off. Im running the 6ls 6012 msd box. Is the 12v wire suppose to go to a ignition 12v or to the battery, cause mines to the battery. What kills the power to the box? i was thinking the tach wire cause the instuctions dont say. thanks guys

its suposed to be switched 12v. be careful with those boxes, they cook. ask me how i know :(

sounds like you have a bad starter.

Second problem is it countinues to run after i turn the ignition off. Im running the 6ls 6012 msd box. Is the 12v wire suppose to go to a ignition 12v or to the battery, cause mines to the battery. What kills the power to the box? i was thinking the tach wire cause the instuctions dont say. thanks guys

not to battery needs 12V with key on and 0V off also check voltage while cranking i found on the fox several will drop to 9 volts or less while cranking and the car will not start

Well i was using the starter from the pullout and i came to the starter selonoid being bad, at least i thought. So i bought a brand new unit from oriellys and still the same thing. Maybe i should run a ground straight to the starter and see what happens?

Also forgot to add that im running my fox 3g 1 wire alt that i modified to fit the ls brackets. i know that dont really matter but thought i add that.

The box is to a 12 volt source that can be cut on and off with a switch, key, solenoid, ect, otherwise, if it has 12, and you start it, it will run till the 12 is removed to the box.

I can't begin to count the number of times I have seen people replace starters and solenoids when the problem was just dirty battery posts. Take a wire brush to them whether they look clean or not.

Fully charge your battery before trying again. Or swap it out for a known good, fully charged battery.

How is your battery's negative terminal hooked to the motor? I hope with a 8 or 4 gauge or larger wire hooked straight from the battery lug to the engine block. People piss me off with "grounds". Always run two wires straight to every load and shit can all grounds.

If you do all the above and it still won't start, try jumpering a wire straight from the battery to the solenoid (I think) S terminal, the small lug you have your ignition switch hooked up to. Sometimes there is excessive resistance in the starter switch circuit that doesn't allow enough juice to get to the solenoid. This loss in current gets more noticeable when the engine is hot. That is why some guys run remote start solenoids.

Pulling the spark plugs should make the engine easier to turn over.

And you need to read the instructions for the MSD box. They are available on line if you don't have a paper copy.

i had the same problem when i did my 6.0 swap in the 89 i had. i tried 3 different starters. the car would crank when it wanted to. all it would do was click. i pulled the entire setup and put it in the 94 i have and have never had that problem. i am not for sure but i think it is something with the ignition system with the fox mustangs.

Thanks for the info guys. I'm currrently running 3 grounds. All terminals and wiring is new from the battery to the sources. Using thick 1 ga welding lead. One ground in from battery to the bolt on the block behind the power steering pump, another is from the battery to the intake bolt using same 1ga wire. ALso have a 10ga from battery to the core support, then also a gtound from the back of the intake to the firewall.

I will clean all once again and try it. My next option and course of action i think will to be hit the S lug on the stater selonoid with 12v straight from the battery and see what happens. like said might be getting a good voltage/amp drop coming through the foxes ignition. If this is the case i will try my remote selonoid again and go from there.


And i have the paper work for the msd box, it says pink wire to 12v source, syas nothing if it should be battery 12v or ignition 12v source. I was thinking the tach wire acted like a relay for the on off for some reason.

On another note i did get the car running with no problems other than this last night. Ran for about 30 mins trying to evac the air out the coolant system.

Now that I think about it when I first put the motor in and had my wire ran up to the battery, I know I turned the motor over 6-8 times by touching the s terminal to the battery post before it was spiced in to the mustangs ignition. Umm now I'm getting somewhere. I remember turning it over to get oil pressure cause it was sitting for around a month.

Try hooking the ignition wires to a relay to feed the starter straight from the battery. You could use a remote Ford starter relay. Lots of write ups on line how to do that.

Another trick is to wedge a screwdriver from the big starter lug to the S terminal.

Yeah I will try the ford seonoid relay this evening. I'm sure it wil fix it. If it works Ill rewire it to a large relay under the wheel well. Thanks for the info so far fellas.

Seems like a lot of grounds... but the ground from body to intake, I would change to the Iron block then go to the body. I remember on the 12volt switched source make sure on the foxbody that it is also on when cranking not just when key is turned on. Dont ask how I know about that:jest: Also I kept the stock Ford Selinoid and it worked great.






Thanks for the info guys. I'm currrently running 3 grounds. All terminals and wiring is new from the battery to the sources. Using thick 1 ga welding lead. One ground in from battery to the bolt on the block behind the power steering pump, another is from the battery to the intake bolt using same 1ga wire. ALso have a 10ga from battery to the core support, then also a gtound from the back of the intake to the firewall.

I will clean all once again and try it. My next option and course of action i think will to be hit the S lug on the stater selonoid with 12v straight from the battery and see what happens. like said might be getting a good voltage/amp drop coming through the foxes ignition. If this is the case i will try my remote selonoid again and go from there.


And i have the paper work for the msd box, it says pink wire to 12v source, syas nothing if it should be battery 12v or ignition 12v source. I was thinking the tach wire acted like a relay for the on off for some reason.

On another note i did get the car running with no problems other than this last night. Ran for about 30 mins trying to evac the air out the coolant system.

a solenoid or relay should get you tightened up..

wired through the ford relay and blam!!!! Starts up like a champ. Thanks guys

I'm looking forward to that first hood off drive down the street with open pipes video.

I'm looking forward to that first hood off drive down the street with open pipes video.

haha yeah. I have full 3 inch to some one chamber mufflers. Ill get vids one day:burn: