What is a CDM?

[RonRaetz]

Does it replace the coil or do I have some of them hiding in there someplace? It's a 2000 Merc 90 hp.

 

[JB]

Re: What is a CDM?

Hi, Ron.<br /><br />I haven' seen that acronym used before, but I suspect that it means Capacitor Discharge Module.<br /><br />If that is correct, it is the module that makes a low/medium voltage pulse that goes into your coils, which make very high voltage pulses for the plugs.<br /><br />I wonder why the new name, though. They have been called power packs for years.<br /><br />Good luck.

 

[RonRaetz]

Re: What is a CDM?

Thanks, thats the name in the Merc parts manual

 

[ODDD1]

Re: What is a CDM?

A heads up for you guys...JB is right on the name...is a different system than merc used in the past, hence the new name....stator and trigger plug directly into the 3 [in his case] CDM's on the side of the motor, they look like coils, plug wires come out if them,and are relatively inexpensive....when you loose spark on a culinder with these things,it may be one of the 'good' units on a working cylinder at fault,trigger and stator return path is needed inside each unit and they do fail....buy a cdm and swap it on each cylinder till you get all your fire back...

 

[RonRaetz]

Re: What is a CDM?

Thanks, ODDD<br /><br />Would a faulty CDM be consistant with this:<br />Sometimes, but not always, slow out of the hole.<br />When OK from the hole, runs great and full 5000 rpm for about 1000 yds then drops back to 3800. Sounds as if its running fine - just won't give more than 3800. Also, changed all 3 plugs, did not help. All 3 plugs always wet.<br /><br />Would love your opinion.

 

[ODDD1]

Re: What is a CDM?

spark or fuel, Ron....you are losing 1 cylinder....a spark test, all 3 should jump a 7/16" air gap...pass this, and I would look to see which carb is running out of fuel...

 

[RonRaetz]

Re: What is a CDM?

ODDD, Thanks.<br /><br />I'll check for spark and keep you posted.