Can't get my 1972 F250 w/390 and auto trans to fire. Ignition distributor is stock with Pertronix Igniter II, Pertronix Flamethrower coil, and Pertronix ignition wires. Truck has been running fine for years. A week ago, it decided not to start. Fired 2 or 3 times then nothing. Investigation showed Pertronix igniter II to be burned. I replaced both Pertronix Igniter and coil. No fire. Replaced high tension wire between coil and distributor, no fire. Verified that there is current to the + side of the coil and a ground pulse from the - side of the coil when turning over. Replaced distributor cap and rotor, no fire. I am completely stumped. Hope somebody out there has a solution to offer. Many thanks...

 

Welcome to FTE

What's the condition of the ballast resistor wire from the ignition switch to the coil? It could have shorted out (possibly shorting out the ignition switch as well).

COLF-12250-A .. Ballast Resistor Wire (Motorcraft DY-37)

#16 gauge wire / Color coded pink / 1.30 to 1.40 ohms / 61" long.
------------------------------------------------------------------------------
D0TZ-11572-A .. Ignition Switch (Motorcraft SW-944)

This ignition switch is used on ALL 1971/72 F100/350's and a few 1970's after serial #G90,001.

 

Bill, thanks for your post. I tested the (+) side of the coil with a test light. There is power from the ignition switch. Also, when I connect the test light to the (-) side of the coil, the light flickers when turning the engine over. According to my Chilton troubleshooting schematic, these are both good signs. Do you still think there could be trouble with the ignition switch or the wire?

 

Is the seconday coil wire firing when pulled from dist. and held near ground source?

 

No fire from the secondary coil wire when held to ground. Replaced the coil and still no fire!

 

Dumb question but.......did you double check all of your conections at the coil and distributor to make sure you're getting good contact? I always try to check the little dumb stuff first. Also could be getting too much amperage to the distributor, could have "burnt" your new ignitor out. Probably some reason for the first one burned down. That would be my next move anyway.

 

Sorry, just reread first post.

The coil wire is good right?

 

All, not sure how to check the amperage (measure and specification) to the coil. Yes, the high tension cable between the coil and distributor tower is good. I'm baffled!!

 

Is the spark plug rotor turning in the cap?

Do you have fuel?

 

Did u set the air gap on the pertronix ignitor? Is the dist. bushings still good(no side play). I'm grasping here. Is the dist. ground still connected? Red wire of Ignitor to + on coil. Black wire to -. Ignitor 800 827 3758.

 

My only advice to you is to remember that just because you have replaced a part (even if it's new), it doesn't mean that it's a good one. Once you feel you have done everything and are still unsuccessful, test the parts you have replaced. On rare occasion a new part will not be good, or another existing problem will cause the new part to go bad immediately. (i.e. check the new ignition module to make sure it isn't burnt too). Once you have experienced this, you will know true frustration!

 

All, thanks for you advise. Will try each and every and see if they help. Will post again afterward.

 

What kind of spark does the plugs show? Should be a blue/white spark. Or pull a plug wire and hold it 1/4" from plug tip. (With an insulated something). We assume the carb shows gas.

 

did you turn the distributor at all (timing) ?
or pull the rotor off and put it back on the wrong way?
did you pull the distributor out at all ?
could be you fixed the one problem but gave yourself more problems
could be 180 degrees out, and although the harmonic balancer shows tdc, its not actually at tdc of the compression stroke, its at tdc of the exhaust stroke
are you getting spark at the boots of the wires?

 

Thanks to all for suggestions. Nothing worked. I finally replaced the distributor with a reman. unit, went back to breaker points and condensor and she fired immediately. Am assuming that the replacement Pertronix unit (read my original post) was bad or burned out too although they are supposed to be protected from high voltage. Think I will just follow another reader's advise and replace points with each oil change and avoid the aggravation. Again, thanks to all for your help.