mercruiser ignition control module?

[Fun Times]

Re: mercruiser ignition control module?

The only thing left is the ICM. Does anybody know if a merc dealer can run a diagnostic on the ICM to determine if it is bad or does it just get replaced when you run out of cheaper options?

dubs283 described how to do this test the best.

If you set your meter to dc volts and connect the positive to the negative side of the coil and the negative side to a good ground, with the ignition "on" hold the white/green wire from the module to ground for a few seconds, if the voltage drops to 7-9 volts, then returns to 12, the module is good.
http://forums.iboats.com/showthread.php?t=444003&p=2970677&viewfull=1#post2970677

Another thing you may want to try is graphing out your engine timing with a timing light.
While in base timing mode make sure your timing is around 8-10 degrees before top dead center, then make sure it's advaning up to around 32 degrees at about 3500 rpm. Right now the idea is to see that it is advancing too??? At this time i'm not sure what your exact numbers should be on your engine, But this should help give you an idea as a starting point.

How to set base timing,
http://www.perfprotech.com/store/articles/mercruiser-engine-timing.aspx

Also check the actual temp of the module with a infrared temperature gun.

 

[Gorillaw]

Re: mercruiser ignition control module?

I quess it's OK to quess you have Thunder 5 ignition?
Who's to say the sensor didn't fail again? Typically, an ICM will create a "no start" situation. The sensor, was it OEM or aftermarket? Are you sure you have a V-8 rotor & wheel assy? V-6 will fit a v-8 & raise hell as your describing. Check these things out.

Think you hot wire that engine @ the engine? Disconnect the main harness & fire it up. Won't have any gauges but that's fine. Doing this will isolate the dash from the engine.

I had a very similar problem with my 357 mag bravo. Hard to restart once it was warm, loss of power that would come and go, for over a year, until the ICM melted down. This diagnostic helped me find the problem.
http://forums.iboats.com/attachment.php?attachmentid=151280&d=1339249085

 

[Don S]

Re: mercruiser ignition control module?

I had a very similar problem with my 357 mag bravo. Hard to restart once it was warm, loss of power that would come and go, for over a year, until the ICM melted down. This diagnostic helped me find the problem.
http://forums.iboats.com/attachment.php?attachmentid=151280&d=1339249085

That chart won't help him a bit, it's for a Thunderbolt IV, the OP has a Thunderbolt V ignition.