[GERKE66Mustang200Ci]

I have a 1968 engine with no spark, so far I've replaced points,condensor, and coil. I read 5.5-7 volts when cranking the engine over and testing the coil. Battery reads 12.25, that should be enough to give even a little spark, right? I did jump it earlier and it read 12.6 after 15 min of charging and taken off the jumper cables and got a little spark off of the coil plug wire. I am in this position because I had a misfire that would come and go. I diagnosed it to spark, and then after letting it sit a day, I fired it up; it did fire up then when i gave it any more gas than 1/2 pedal it would die and act like it was flooding, but it was not flooding. Then after messing with it I gave it more than 1/2 again and it lefted me stranded in my driveway and would only crank no spark. And that is when I started replacing components. The points are gapped to .27 and the condensor and points are Echlin. I tried routing a jumper wire from the battery to the coil to bypass the ignition switch and resistor wire and still nothing but I did read around 12 volts from coil when I did that but still had no spark. I admit I am stuck. Is this really just all from a low battery? It still turns over just fine. Any responses would be greatly appriciated.

:Gerke

 

[Cobrajet67]

Supposedly, voltage over 7.5v will fire an ignitor in a 12v system.
If the coil is getting 12v directly, it tests good(look up how to test a coil), and you still have no spark then it's downstream from there. It sounds like the problem lies within the distributor or the coil wire.
Have you checked to see if the points are physically opening/closing? Check that your points aren't grounded or stuck open.
Have you checked the cap and rotor? A crack in the cap or burnt contacts will cause weak, intermittent, or no spark.
New replacement parts are often of questionable quality so I wouldn't rule them out. Test the points and coil. The condenser I'm not sure can be tested.

 

[07redstang]

The gap should be .027 on the high spot of the distributor cam lobe.

 

[Yadkin]

The coil should see full battery voltage with the starter engages, and about half that when running. During start the coil is powered by the starter solenoid. During run it is powered off the ignition switch and a pink resistance wire embedded in the harness. There are no fuses in either circuit. Study the ignition wiring diagram and check that your connections are correct.

 

[GERKE66Mustang200Ci]

okay so i checked the points they are opening the coil is good i tested it with the multimeter and got good resistance also tested the out put the output was at 4.5k ohms. connected it up to my truck to give it a jump and still got 5.5v at the coil in the start position at the pack with approximatly ~13 volts at the battery but when the coil plug wire was grounded to the frame still no spark. i checked cap rotor everything else when i was trying to start it the coil pack read 8.5v with the engine turning over. could that be bad ignition switch or the resistor wire going out?

Update: I took of the ground wire off the ignition coil and tested voltage at the coil again and got my full battery voltage with positive on the + of the coil and the - on a bare metal surface connected to the frame. I assume this means that the resistor wire was bypassed at some point tin the cars lifespan.

 

[Grimbrand]

It could just mean you had a bad ground, too?

 

[65falconspock]

I know that 12v isn’t as particular as 6v stuff but a good ground is definitely needed nonetheless.
so far nothing has been said about plugs , replace them (there cheap 2.50 a piece autolite 46 I think don’t quote me)
How does the inside of your cap look ? Sooty and growing stuff or just a little black?
-Blake

 

[07redstang]

I don't understand what you are doing. With the coil grounded you will never get spark. The points supply a pulsed ground to the coil- terminal to fire each plug as the distributor turns. The ignition switch signal runs through a resistance wire to lower the voltage to the coil with the key in the run position. The starter solenoid supplies full battery voltage to the coil+ terminal when starter is energized.