4.3 With No Spark

[Gary Bobbin]

I have a 2003 MCM 4.3l mercruiser stern drive with thrunder bolt v ignition. took boat out 3 times this year, last week engine would not start. I used the flow chart for trouble shooting as posted in this forum and my repair manual. I have 12 volts at the coil and do not get a spark when tapping wht/ green wire to ground. I put a new coil in. same problem. I thought I would bench test the coil since it was new and possibly received a bad coil. I put the battery and coil on my bench. Ohm readings were good on old coil and new coil. I put 12 volt to + on the new coil. I used a gap tester from center of coil to negative on battery. I then connected a lead to negative on battery and tapped the other end of lead to the - on coil. I did not get a spark ? Am I missing something ? should I be able to test the coil on the bench or does the ignition module do something I am not thinking of. At this point, I went through the flow chart trouble shooting and down to no spark, replace ignition module. just wanted to check before spending $300 on the new module.

 

[alldodge]

Yes testing coil on the beach the way you did is ok

Just to check finds
You did get 12V on the White/Red lead?
You did strike the White/Green lead at least 2-3 times a second, that was coming from the module (not distributor)?

If all correct, and you have good connections to the module, then I would suspect the module

 

[Gary Bobbin]

Thanks. you are correct. there was a quick disconnect on the green and white wire, I grounded the exposed connector which went to the distributor. when i grounded the side that goes to the module (as indicated in the flow chart), I get a spark.
will replace the ignition senor
I still don't know why i can not get a spark from a coil when I bench test it. the ignition module must be doing something I can not simulate on the bench.
thank you very much.