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.

 

[rusty ol ranger]

Yellow means the spark is weak.

Kinda 50\50 on rather it would fire or not.

 

[Uncle Gump]

Did you test it with one of these?

 

[Hoosierman]

Thanks Rusty.

Uncle Gump, I did.

 

[Uncle Gump]

And you got a snap?

 

[Uncle Gump]

Meaning a spark with an audible "snap"

 

[Hoosierman]

As I recall, yes.

 

[Uncle Gump]

Well... if it will jump the gap on that tester... you should be good. IMHO... a weak coil or the like would never jump that gap. It was designed for testing HEI.

 

[Hoosierman]

I decided to try to pull a code using the Check Engine light method, but when I turn the key on, the light comes on for a fraction of a second and never flashes for me. I don't have an analog volt meter, so this may be the only method I could for the moment. Doing this has helped me diagnose issues on some other older vehicles before.