96 GTX no spark issue

[jchance]

One of my GTXs has a curious issue. I rebuilt the carbs recently due to poor performance. Reinstalled them and it ran perfectly. I got RPMs in the 6.4K range with good pop out of the water. Don't blame my wife but she took it out, ran good for around 10 minutes and suddenly dropped to 2K and limped back to our lift. It sat for about and hour until I had time to look at it. It will turn over but did not try to hit at all. Since then it has had no spark. I checked the compression-all good. I pulled the plugs and replaced with new-no change. I have checked the fuses-all good. I have looked at the rear box and do not see any issue with either the ground to the battery or any of the connections inside-- nothing. The voltage while cranking is good. I have swapped the front box with a spare but have not had time to program a key to it so will do that tonight. Any other thoughts?? If I still have no spark after all of that then I am thinking my only other option is the stator sensor and I really don't want to pull that cover off if I do not have to.Thanks!

 

[Grim]

Check your coil, see if it is toast. How did you check for spark?

 

[jchance]

I used a spark tester first without any sign of a spark. I next closed off the gas, pulled the plugs, blew the remaining gas from the cylinders and grounded them to the head; still no spark. I have a spare rear box to try if all else fails. As I said in the original post, first step after I finally get home tonight is to program a key to my spare front box and see if I get a spark.

 

[artr]

This is a good video that goes through a 96 XP ignition system with no spark which is identical to the 96 GTX ignition system.

 

[Saltydawg1976]

Yes that is definitely a good video. It actually shows you how to test the coils. I also found a fuse in the rear box that looked like a plug until I pulled it out. Other then that it's probably a cup or stator problem.

 

[jchance]

Here's a question: Would a coil primary resistance of 50+ ohms when it is supposed to be in the 0.3-0.6 range be enough to kill the spark. Mine tests good on the secondary but very high on the primary. Thanks!

 

[artr]

Increased resistance in the primary can affect voltage and current. A loss of 1 volt on the primary can reduce the secondary by 1000s of volts and have an effect on spark. If your measurement is accurate it is about 100 times over spec and I would replace the coil.

 

[jchance]

Exactly my thoughts. I pulled the rear box to check/clean everything and thought for grins that I'd check with my spark tester again. There was no apparent problem inside the box. This time it was night and I didn't have a work light over the area. when I hit the starter I saw a VERY faint glow to the test light. It was there each time as expected but very faint. I would have missed it under daylight or with a bright light. Awaiting a new coil as my spare is at the lake garage. Will post hopefully in 2 days if that solves the problem.

 

[jchance]

Changed the coil and runs like a scalded dog again. Thanks all!!

 

[POPPS]

Way to go!!