Low spark issue?!?

There is a resistance wire for the ignition system that comes from the ignition switch and goes to the coil, it reduces nominal 12v (12-14.5V) to 7-9v so you won't burn up or overheat Ford's ignition components. Sounds like you have weak spark for sure, could the coil's wiring could be reversed (car will still run, just not good though, also will cause the weak spark output). Just a thought. Todd

Ford's ignition coil require only 7-9 volts to obtain full output, if you feed it 12+ volts the coil will overheat. If you look at the coil there is a bat terminal and a dist. terminal, if these wires are reversed low spark output will result. This is assuming you are using a point style ignition, the later Duraspark horseshoe coil connector is almost a fool proof type of connection. If you have or are using a Duraspark ignition in place of points, you shouldn't have 12v at the coil while running(you should see full 12v at the BAT terminal when the key is in the start position only). You should still see 7-9v while engine running(or key in the run position), if you have 12v at the coil while running the coil will overheat and the Duraspark module will work erratically and/or shut down due to overheating. Please give some details, with pics if possible. Todd

Edited by aquartlow - 14-April-2014 at 4:20PM

I tried an MSD Blaster 2F coil with my factory Duraspark ignition, the coils spark output energy sucked big time(yellow spark with plug gapped at .030"). I installed a Jacobs ignition with a Jacobs Ultra coil, the spark output was at least 3 times that of the MSD coil and I was able to open the plug gap to .045"(probably could have went to .060" with the output I saw). The Jacobs crapped out finally(had it 15 years) and then I installed a Crane HI-6 with an LX-92 coil, if you pull a plug wire off and the ignition "bites" you, you will piss your pants and forget your name for a moment or two. Try a different coil, and wire it by the coil manufacturers recommendations. The 2F was a direct replacement(albeit a sorry, lower performing coil compared to a factory Duraspark coil) so the horseshoe connector fit it. Good luck. Todd

Also make sure that you have an external resistor coil. If you have an internal resister coil like your buddy, it will not work with low voltage.