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Ignition Control Module....keeps blowing.....?

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Blackfin27

Contributing Member
350XL 1996 TB....lost power underway 3 weeks ago, came back and replaced Ignition Module all good.

While underway yesterday same thing same engine, limped home. Cant start etc.

My mechanic replaced it again this morning, ran out and trolled for several hours.

All good, then noticed a slight power drop Port again while trolling....but seemd ok.....picked up and again the same engine shut down and limped home....brand new Ignition Control unit lasted 6 hours...

Engine doesn't give any warning except a slight power drop just before the shut down. Im on 3 Ignition Control Mods now in a month and 2 in a week and maybe a 3rd.....Pick up coil in new this season.

Any best guesses....would a voltage spike fry the ICM ?

I cant afford to repower just yet. Thanks.
 
Are you sure it is the ignition Module ?? How did you proof it and how did the "Blown" ones get proofed??
 
You need to do a full diagnostic after replacing any part? Do both motors have their own separate battery and charging system and volt meters? Are you connecting a battery charger when boat is docked and are the batteries isolated from the system when charging?
 
You need to do a full diagnostic after replacing any part? Do both engines have their own separate battery and charging system and volt meters? Are you connecting a battery charger when boat is docked and are the batteries isolated from the system when charging?
 
makomark said:
GM modules or aftermarket?

proper heat transfer compound used?
Click to expand...

We got the GM's but made elsewhere. Installed new harness connections to the ICM. Heat transfer grease applied. Have both engines with new ICM and harness. Will be running the boat and see, typically, this happens to me after several hours of trolling or idle it seems.
 
Blackfin27 said:
We got the GM's but made elsewhere. Installed new harness connections to the ICM. Heat transfer grease applied. Have both engines with new ICM and harness. Will be running the boat and see, typically, this happens to me after several hours of trolling or idle it seems.
Click to expand...

Ok so here we go.....several short trips no issue then....trolling for an hour and the Port engine just shuts off, let it sit a few minutes and it fired right up.
No bells, no gauge flutter. So with a new ICM now I have a stall....??
 
What is the story with the ignition coil? Age? Is this the one inside the distrib?
Not the pickup, the high voltage coil.
 
My question also are the coils getting hot? Make sure the ignition modules are getting battery voltage and put a ballast resistor for coil posative if they are getting hot and see if she stays running. The ignition coil should only get warm during normal operation.
 
Are you sure it is an electrical problem and NOT fuel....

hate to bring up old history but I had the same problems, same symptoms and it was the anti siphon valve that allowed the engine to run about 3 hours and then shut down. Would not start for about an hour or so. The "ball bearing" in the valve was covered with "stuff" and when it got wet...(in about 3 hours or so) it stopped fuel from getting to the engine.. Ball bearing "gunk" dried up and it would start again.

The mechanic I had , (not at home port) changed just about every electrical part known to mankind...had the same problem. Back home I pulled the anti siphon valve on that engine and for less that $4.00 problem solved.

Good luck....

How did you prove the ICM was at fault???????
 
willow said:
Are you sure it is an electrical problem and NOT fuel....

How did you prove the ICM was at fault???????
Click to expand...

Great question, and can be easily answered in one of two ways.
Does spark go away when the engine dies, OR
Put on one of the recently "defective" units. What happens.

If its indeed spark, I'm voting ignition coil; heats up and turns off, cools and turns on.
 
If it turns out to be you ignition module try thermal grease between the module and the mount. heat kills the module very quickly, it cured my problem.
 
Low voltage will kill a ICM also make sure the module is getting battery voltage while running and a good ground?
 
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diver_dave said:
What is the story with the ignition coil? Age? Is this the one inside the distrib?
Not the pickup, the high voltage coil.
Click to expand...


Update today....swapped out Port Ignition coil.....it failed on the other engine so we think thats the culprit.....we thought these had been replaced last season but we may have missed these...keep good records !

Thanks for your help.....lets see.
 
Just put your hand on the coils when the engine is running if it gets hot just install a ballast to coil pos and see how good it runs. It should jump a open air gap of 9/16 minimum on all the plug wires.
 
Blackfin27 said:
Update today....swapped out Port Ignition coil.....it failed on the other engine so we think thats the culprit.....we thought these had been replaced last season but we may have missed these...keep good records !

Thanks for your help.....lets see.
Click to expand...

Ran the boat Saturday after the new ignition coils were installed.....no stalls or cut outs this trip so fingers crossed we got it this time !
 
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