[kblancha82]

Hi All. I have a 73 Mach One with a 351C 4bbl and a 4speed. I currently have my dash appart and all my guages are disconnected. I had to move the car the other night and it will not run when the ignition lock is in on position. If I hold the starter engaged it will run until i release it into on position. Does my ignition power run through one of the guages or did something go dead over the winter??? Thanks

Kyle

 

[MustangBilly]

There is a starter by-pass wire going through the 14401 wire loom. Possibly you may have disconnected a connector that it runs through so look for any loose connector. I myself have never seen it run through the dash guages though.

 

[kblancha82]

Would this connector be behind the dash somewhere? Like maybe I pulled it out on mistake while pulling the guages?

 

[70_Cougar]

When you unpluged the tach it disconnects the power to the coil. The reason it fires up when in the start position is that it gets power from the solenoid which is the source of 12 volts for starts only that bypass the resistor wire. I hope your cluster has a tach. John

 

[MustangBilly]

Sorry, I miss-worded " starter by-pass" wire. I meant resistor wire goes through the 14401 wire loom. Also, I have to diagree with 70_Cougar (sorry), the tach runs on the negative side of the coil. Here are two links of pictures of a 67 dash assembly and wire diagram. I don't have the year you have but the concept is the same.

http://fatima.epconline.com/cars/67ignit1.jpg
http://fatima.epconline.com/cars/67instr.jpg

Bill

 

[DB65]

I have to agree WITH 70 Cougar... The ignition IS run through the tach or at least it was back in my 1970 Mach I with 351 4v. Sure sounds like the problem you're having to me. You should be able to jumper the tach connection and everything should run fine.

 

[MustangBilly]

OK, if the ignition is ran through the tach on your 1970 Mach I then how is it that every other tach or dwell meter is connected to the negative side of the coil?

 

[DB65]

We may be trying to say pretty much the same thing two slightly different ways. It may well be to the negative side of the coil but I do know that if the tach circuit opens (mine was intermittent in the tach itself and a real bummer to find) the engine will start but die as soon as the key is moved to the run position and this is what the symptoms as described seem to indicate. I guess it's my opinion that the tach is in "series" with the coil and as such will not allow the engine to run if there is an opening in the circuit. I know jumpering my tach connections got mine running some 30 years ago.

 

[MustangBilly]

67_70_now_65, I understand what you are saying but only if the negative side was grounded and that would affect cranking ignition and running ignition. An open circuit shouldn't cause any problem. As you know, the points do the grounding for coil saturation. When the points open the builtup voltage in the primary side of the coil wants to find a path to ground so it goes through the secondary windings and higher voltage goes to the distributor cap and the to the plugs. The tach measures the occurence of the dwell time (points closed) to produce the RPM. So disconnecting the tach will not affect anything.

Anyway, this is not really helping to solve his problem. I would recommend checking voltage at the positive side of the coil while the points are open and the ignition switch on. If there is no voltage then I would trace the positive wire from the ignition switch all the way to the coil. I only had a wiring diagram for a 67 so he should get one for his model.

I don't mean to act like a know-it-all or offend anybody so I apologize, but I am using my 25 years of experience of being a professional ASE Master Technician and having worked at a Ford dealer in the 70s. I just wish I had the correct wiring diagram to be 100% sure.

 

[70_Cougar]

Billy, it is well documented on this site that a open tach will cause a no start situation. Only the points are in the neg. side of the coil circuit. In the 60s and early 70s ford used tachs that were current sensing and were in series between the ignition switch and the plus side of the coil. If you break this circuit it will not run! Strange way to run a tach but YES this is how Ford did it back then. John

 

[gtrman59]

On my '72, there is a two wire harness that hooks to a pigtail that comes directly out of the in dash tach...if it is dis-connected the car won't run in with the key in the run position....find the two wire harness(both are red wires) and jump them together and car should start

 

[MustangBilly]

Cool, I learned something about the dash. I wished that I had the wiring diagram. I'll keep my mouth shut.