Start and Ignition Problems on 71 Demon

After further testing, spark at coil is weak and intermittent, cranking engine over gets a small spark at coil every 5 sec of cranking or so....any ideas? Tried changing the coil out, no change...

Mark

just a thought, but verify the ballast connectors are where they are supposed to be. i once had a locating pin on a ballast connector that was broken off and the connector was upside down and giving me a weak and intermittent spark. it wouldnt hurt to try a different ballast resistor. seems a lot of folks having problems with them,,, you could also try a different EI box. i know this falls into the category of "throwing parts at it" but if it was running before , it has to be something simple, maybe you just bumped something loose