1977 Ford F250 , 460 auto, stock DuraSpark II ignition.

I don't seem to be getting any spark when I turn the key to "Start". If I time it just right, when I release the key to the "Run" position, it will catch and run fine. Other times it'll kick back and try to run backwards. I've disconnected the coil wire and held it next to a good ground, cranked it over to "Start", and no spark, but just as the key goes from "Start" to "Run", there's a couple of sparks. I've never run into this problem before. It's got me stumped. Any ideas out there?

Thanks in advance....

Oh, I've replaced the ignition switch and no change. I get the same problem when I "hot wire" it and jump the solenoid under the hood.

 

I have seen this problem with the ignition ( brain box) going bad. If you take it off the fenderwell you might see the underside stuff soft and kind of burnt. Anyways. I think it could be the ignition box.

 

Not familiar with your system but it is a classic sign of a bad ballast resistor (if fitted).

 

IIRC, on the '77 the power for the fuel pumps and the ignition on startup are off the second small terminal on the starter solenoid. If the contact goes bad no ignition. I would just jumper the wire to 12 volts and see if the pump runs and you have ignition when you crank the motor.

 

Bear...no pumps on this truck...well, no electric ones anyway. I get spark with the key in the "Run" position, but no spark in the "Start" position.

 

If there is a second small post on the start solenoid (toward the rear) then that would be the power for the hot start for the ignition.

 

Bear....just tested and there's lots of juice at the "I" terminal on the solenoid. The test light gets really bright when cranking. I also checked all the wires from the 2 plugs at the ignition module on the fender apron to the coil/distributor, and all check out fine. Looking more and more like I need a new module. While I had the module off the truck, I cleaned the mounting areas, in case the module needed to be grounded. There's a "Standard Auto Parts" one there now, so it's been replaced once (at least) already.

 

I'm real partial to changing both the box and the trigger module (in the dist.) at the same time. I've seen a new box get fried by a bad trigger module that fried the first box.

 

Is there a way to test the pickup inside the dizzy? The distributor isn't that old. I did probe the contacts while I was checking the harness wires, but I dont know what the correct values should be. Its a ProForm DuraSpark replacement dizzy.

Thanks.

 

Last time I test one was 20 years ago and my memory isn't that good any more. I would have to dig out a manual and check to find out.

 

I "Googled" it and found the pickup coil should be between 400 and 800 ohms. Mine checked in at 565, so I guess its OK.

 

Update on this thread....swapped in a known-good ignition box today and the ol' girl fired right up!

Thanks for the help, y'all.

I appreciate it!