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stuart

No Start Problem, Has Spark and Fuel

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Need some help diagnosing an electrical problem.  To begin it's a 1969 Mach 1, 351 4V with factory tach and running Pertronix III and Pertronix Ignitor coil.  Last weekend it cranked up fine and ran briefly, then died.  After that when turning the motor over it would catch and fire once, then die. I'm getting the Alternator light in the dash, but tachometer isn't moving.  Carburetor, fuel pump, battery, starter, and solenoid all checked out ok.    I swapped back to Ford coil and points and no fix to problem.  I pulled the plug from back of ignition switch and found what appeared to be a short where the black w/green and dark pink connect at the plug. Installed a replacement pigtail and no fix.  I'd like to fix this myself and not have to drag her to a repair shop.

Should I be suspecting a fault in the tach, or start tracking down a short or burned fusible link somewhere in the harness?

thanks,

Stu

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Well you already said you're getting spark so its probably not electrical. Are you getting 12V to the coil when starting? If you have a VOM connect one side to chassis and the other to the Bat. side of the coil. See below for the expected voltages. Make sure your battery is topped off. It could be a timing issue, a bad capacitor or point gap.

BTW, there are no fusible links on a 69, they started using them in 70. This schematic shows you how it works:

ZYTTIEt.png

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You might try putting a jumper wire between the battery and the high side of the coil.  Do this only when you know it does not work normally, and then do it for only a few seconds.  Doing this will bypass the ignition switch, tachometer, resistor wire, and all dash wires.  I have tried this and it proved my fault was in my coil.  In my case, as soon as the coil warmed up, it would stop working.  I tried my trick when the coil was cold and it showed that it worked.  I connected the coil back up to the engine harness, and started the car.  It ran for 8 minutes and died.  I then connected 12 volts right to the coil, and this time it would not run.   I replaced the coil, and it has been fine for years. 

So the next time your stops working, put a wire between your battery and the coil, and see if that works.  You need to do it quickly, when the coil is still warm, to confirm that is the problem.   

This might not be it for you, I am just passing on what I found in mine.   The coils stop working after they warm up. 

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