I just rebuilt my 72 cougar convertible 351c 2v and turn her into a 4v. while the motor broken in. Having a problem with my ignition. Had to jump the coil while doing the brake in. Intermittent power to the coil and problem with my tach. Unplug the tach and it works for a bit then cuts out. I checked the wiring under the hood and it seems ok. The only thing I did was change the wiring for the voltage regulator. Oh and the wire for the selnoid for the old cab. I cut that out and extended it for power to the choke on the new Holley 600. I did find a wire connector at the base of the steering colum that when I squeeze the connectors together I get power to the coil. Not sure if this is the problem for sure.
Sounds like the connector is your issue. You can remove individual pins from the connector and some times you can squeeze them so they make a better fit and then re-insert them. When you changed the solenoid wiring that could have put a bigger load on the circuit and the additional current might have heated up an already bad connection. Why did you change the voltage regulator wiring?
I find that if I squeeze the 12 pin connector that leads from the steering column I can get power but if I move the connector/wire harness I power is gone. But when I get power to the coil I’ll get 12 volts with the wire unhooked from coil (great right) but when I hook it up to the coil it drops down to 5 volts!.I moved the coil from the drivers side to the passenger side of the motor because I just rebuilt the motor and if I were to put it back where it used to be I would have to undo a bolt that torqued the manifold down. So there was a short bolt on the passenger side of the manifold that did not help bolt the manifold to the block so I used that for the coil. Now could that be a part of my problem? The coil bolted to a aluminum manifold! and not the longer bolt that would ground to the main block?
The power wire that feeds the coil is a resistor wire. The voltage should drop to about 5 or 6 volts under load, that is hooked up to the coil with the points closed to complete the circuit.
So
I changed the ignition switch and that seemed to have worked. It turns out that when I was squeezing that 12 wire connector I would get power but it wasn’t the 12 wire connector it was the connector beside it which turns out to be the connector for the ignition switch. The ground wire on the ignition switch was broken so when I was moving the connectors around it would ground and not ground. Hence the power no power.
So that fixed one problem but cause another. Now when I start the car, it starts but you have to turn the key back or else the starter stays ingaged. Pain in my ass! I tried to adjust the ignition switch up and down. Didn’t improve it.
And now my big problem THE TACH WIRE!
The tach wire goes to the neg side or distributor side of the coil. Mine has 12 volts coming from it and when I touch the turminal the car dies. I don’t think there is supposed to have any volt! Right. Where dose the tach wire come connector look like?
Dose anybody have a 72 cougar wire harness diagram they could share?
If you have an OEM tach, the tach wire goes to the + side of the dizzy, not the negative side. If aftermarket, that line should not have power.
Aftermarket tachs have three lines: ground, power for the gauge, and tach signal.
So
Your saying both wire to the coil go on the battery side of the coil and the one wire from the distributor goes on the negative side of the coil?
I’m sure when I took the wires off the coil two wires were on the distributor side.
If both those wire have power (12 volt). I can hook them up together on the battery or + side of the coil?
The coil should be powered through the tach, meaning the tach is in series with the coil. So power goes through the ignition switch, then through the tach, then through a resistor wire and on to the + side of the coil. The wire on the - side of the coil goes to the distributor. (do you have a Pertronix by any chance?) There may also be a second wire to the + side of the coil. This would come from the I post on the side of the starter solenoid. It supplies a full 12 volts during engine cranking. I don’t know how the wiring harness is arranged so this wire may tee into the harness and not be visible.
I have to be honest with you. I don’t know what a Pertronex is. And what year Cougar are you talking about? I don’t think this matters but mine is also a convertible. Just throwing that out there.
The wire that is supposed to feed the coil or take from the coil has 12 volts. I’m sure it never had voltage before. I’m pretty sure the distributor side of the coil is where the tach wire is supposed to go. If I connect the tach wire to any side of the coil the car stalls right away. If I hook up the coil wire to the battery side of the coil without the coil wire hooked up the car will start and the tach works! Doesn’t make sense! Almost ready to get out the sledge hammer! One step forward two steps back
The basic circuit is the same regardless of the year '67 through '73. Is your car an XR-7 with the built in factory tach or do you have an after market tach. I was thinking XR-7. Convertible is not a factor in this area. What does this mean: (The wire that is supposed to feed the coil or take from the coil has 12 volts. I’m sure it never had voltage before.)? The coil has two posts. The + post is fed by the ignition switch and should read 12 volts or so with no load and about 6 volts under load. The - post goes to the distributor. When the ignition points inside the distributor are closed it completes the circuit. This is where you will measure 6 volts. When the points are open you will measure 12 volts. Maybe you can take some pictures and we can see what you are seeing.
As I tried to say before, Ford’s tach design is not standard. The tach is in series between the ignition switch and the battery side of the coil. This line is only hot with voltage with the key in RUN or CRANK. The negative side of the coil goes to the points in the distributor, or some sort of a “ground” in aftermarket distributors.
Aftermarket tachs are voltage-sensing devices, and their signal line attaches to the negative side of the coil. These aftermarket tachs require power to the gauge, but that’s all under the dash and should not get power from the engine compartment.
What you haven’t described adequately to us is whether your tach is an original Ford tach, an aftermarket tach, or a tach that has been substituted in the original dash cluster. Since you talk about a tach wire that when touched to either side of the coil (the car stalls), then that wire cannot be the Ford coil wire, as the car cannot run without the tach in series, with one exception. If the two pin plug going to the tach (to enable it to be in series) is jumpered, the car can run, but nothing you can plug into the tach mating plug at this point can make the Ford tach work. If that tach is not a Ford original tach, but an aftermarket installed in your dash, then its signal wire should go to the negative side of the coil, and the gauge power line needs to tap a RUN-only or ACC-powered line under the dash somewhere. It also needs a ground, whereas the Ford tach uses no ground.
Clear as mud, eh?
Sorry guys
I was away for a bit and didn’t have a chance to answer.
The tach is original stock tach for an xr7.
It just getting more confusing! From what I have researched the wires that come from the tach and in in the engine compartment is a two wire plug that changes to a single wire that go to the coil. While since I installed a new carb that did not need a selniod for carb I cut that wire and used it for the electric choke. The reason I tell you this is because those two electrical connectors are the same and for a minute I thought maybe I cut the tach wire and rerouted to the new electric choke. But it looks like I did not. So that’s about all I did except put a new electrical plug for the voltage regulator. But here were it gets weird! So the two wires that go to the coil and for some reason they both have power and I can only hook one wire up or else the car won’t start. If I hook up one wire the cars runs fine with no tach if I disconnect that wire and hook up the other wire. The tach works and the car runs but here’s the kicker that wire that is making the tach work is NOT the wire from the tach! And my timing light has a wire you clip to the distributor side of the coil ( negative side) and I don’t even have the clip that wire for the timing light tach to the coil and the tach works! And is the correct reading! I bought the wiring diagram for a 72 cougar but might as well be in Chinese. I’m not good at reading it. I guess I’ll take the dash apart and chase the tach wires from the dash to the coil. I hope I didn’t just confuse you all. I’m just soooo frustrated! Never should have touch the car it ran perfect before. I just got greedy for a little more power!
I will take a picture of the wire diagram and if anyone could give me some answers to a few questions. 1. Is the power coming from the tach to the coil? 2. If there is not supposed to be power coming From the tach. Then why am I getting power from there
Here one more. If anyone was an idea please let me know your thoughts. Thanks
Please describe the wire colors for the two wires going to the coil. I presume you mean the + side of the coil for these two wires. In a stock configuration, there should only be one wire on the + side of the coil (red/green); and the one wire on the - side of the coil should be going to the distributor (black).
Well that’s one of the problems. They have been changed in the past so they are different then what they should be. I took a few pictures of the wire connectors that are located on the back of the motor drivers side. I also looked at the wiring diagram and I think I see that there is a connection between the voltage regulator and the tach! If I’m looking at it correctly. Not good at reading them. That maybe my problem. When I put in the new voltage regulator connector. If it is some how connected to the tach that would make sense
Here are the pictures of the wires and wire connectors at the back of the motor drivers side
The one you hold in your hand contains the proper line to the coil: third from the top as shown in the picture. The other plug should not be part of the circuitry. I can’t identify it, but it appears one wire has been removed from the left side. It is probably for the carb solenoid or for an electric choke, or some weird emissions control item.
Third from the top is power to the coil? So from what I have been looking and reading the connector that is two wires and changes to one wire. I think that is supposed to be my tach. Not total sure about that.
On the connector that has the power to the coil. Do you know what the bottom wire ( black with looks like gray or green strips) is for. On my harness it has been cut and capped off.