ignition troubles

[presidentpoo]

so i replaced the starter on my 95 mtx yesterday and that plus the fuel pump got it cranking.starter is turning over and the fuel pump is kicking on but it wont start. i took a plug wire off a plug and put a screwdriver to it while still on the coil and cranked but got not sparks at all. how can i tell if its the coil i need to replace or the DIS. im thinking its the coil because it looks to be the original.

 

[ViPER1313]

Usually, the coils on SHOs don't die.

I don't remember the exact diagnostic procedure for no-spark off the top of my head, but check the 2 following things (common causes for no spark conditions)

1. Make sure that the ground strap from the firewall to the upper intake manifold is in place (its a braded, bare wire on the rear passenger side of the motor.) This is necessary for the DIS to operate properly - without it you will have no spark.

2. Check to see if your tach moves off of 0 while you are cranking the motor. If your crank position sensor is dead, your tach will not move while cranking and you will not have any spark.

Assuming that the coil and/or DIS is actually the problem, I'm pretty sure that you can take the connector off of the coil (or tap a wire off of the DIS) and use a multimeter to diagnose if it is receiving the proper firing signals from the DIS. Just forget exactly how that is done (do a search.)

 

[frosho]

If your crank position sensor is dead, your tach will not move while cranking...

Incorrectamundo. The tach signal is run off the cam sensor, which won't prevent spark if faulty.

...and you will not have any spark.

This is correct for a faulty crank sensor.

 

[presidentpoo]

just wanted to update on this. turns out one of the connectors to the DIS was loose causing the no spark. found it plugged it in tight and she started right up