That is the crank bolt - You need a new harmonic balancer.
The balancer is what actually breaks the bolt and then then "walks" off the crank snout. When the balancer moves forward, the vanes no longer engage the crank sensor leaving you with out spark.
This is a weekend job and will cost you about $300 for parts. Check the crank sensor real well to see if it has been damaged, if there are any signs of rubbing then replace it as it will fail at the worst possible time.
You can also go with a BHJ balancer but will need a zero balanced crank pulley to go with it.If you have underdrives then the crank pulley is already zero balanced. You can have your stock pulley balanced, but the BHJ balancer is MUCH heavier than the stock unit so having an aluminum pulley brings the total back to near stock. Cost is much higher but the BHJ is what you want if you plan on doing a lot of mods.
Aaron