A question about spark.

[Hoosierman]

I finally got around to tuning up my '88 Ranger with new plugs, wires, cap, rotor. And I also installed a McCully Racing MK2 TFI relocator kit. I'm having to work bit-by-bit on the truck as I have brakes to do on another and a coolant flush on a third vehicle. Today I wrapped up the relocation job and now the truck only cranks. So I'm following the TFI diagnosis section in the tech library and I noticed that when I test spark from the ignition coil, the spark is YELLOW.

Is a yellow spark a definite problem? My understanding is that spark should either be white or blue, just not sure how imperative it is.

Thanks.