1994 4.3LX Mercruiser random stalling in heavy wake??

[mxracer342]

I found the solution on my boat. The ignition coil was the imposter. It kept shorting and overloading the ICM when the coil warmed up. Must of been the coils expanding and touching each other due to faulty insulation in the Factory coil. After changing it on the boat never died on me since i took it out this sunday and i punched it pretty hard on plane too for way more than 30 minutes at high rpm. Go down to your local oreily/kragen and grab an ignition coil from them with a lifetime warranty included. Just tell them to match it up with a S10 chevy blazer 4.3 (same exact engine that is in your boat and make sure it's a borg warner coil which is the same exact coil as napas echelin). That should give you your fix. If not then another imposter would be a faulty circuit breaker acting like an inductor (talked to a guy with a mercruiser same exact engine). But for your case. I'd say it's just a bad coil (i'm never buying factory GM parts ever again) For me it was definitely a bad ignition coil backfeeding into the ICM ultimately frying it. Oh and lastly if you are mounting a new ICM. Make sure you put lots of thermal paste on it (not dielectric grease) The thermal paste will give the module far better heat transfer and ultimately keep it a bit cooler when operating.

Man thank you for letting me know. My biggest concern was that I'd buy part after part and end up spending money I didn't have to. Can they test a coil at Oreilly's?

 

[Bowboss]

Man thank you for letting me know. My biggest concern was that I'd buy part after part and end up spending money I didn't have to. Can they test a coil at Oreilly's?

You can only Test the ignition control module at oreileys or autozone. The coil you can do with a multimeter and this link while it states it's for a GMC sierra. It's pretty much the same exact coil. It shows you which area to touch with the multimeter to test for Ohms. I unfortunately couldn't test mine because the short would happen when the coil would heat up after a little while with the engine running. But you could always return the coil if that doesn't fix your problem. Another thing to check to would be your pickup coil right in the distributor that connects the the ICM.

http://www.justanswer.com/gmc/7vlqy-gmc-sierra-1500-92-gmc-sierra-1500-tbi-no-start-weak.html
http://www.autozone.com/autozone/re...n-HEI-System/Pickup-Coil/_/P-0900c1528025f555

 

[mxracer342]

So I've come back to this thread with an update. I didn't make much progress in checking wiring our anything else for that matter but the problem has gotten progressively worse. Now it only takes moderate waves to cause the boat to completely die. When this happens it won't start back for a few minutes. It will fire and hit just like it does when you have the run switch turned off...like you've pulled the safety lanyard out. Could this be a problem with the carb? Maybe a bad run/off safety switch or lose wire? I'm stumped even more now.

 

[havoc_squad]

Sounds like either a wiring harness issue in the engine compartment or the console wiring somewhere.

If the engine immediately/instantly reacts upon impact of wake on boat, you have somewhere a very bad electrical connection.

Carbs do not cause sudden power loss, it takes at least a little time for carbs to affect engine performance. Remember, electricity travels faster than fuel does. If you are not going through fuses or tripping circuit breakers, this has "open circuit" problem written all over it. Whether that be corrosion, frayed wire, loose wire nuts, etc.

Even it if was an electrical fuel pump issue, it would take a second or two for the carb to run itself out of gas if it stopped pumping.