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Conversion from points to electronic ignition OMC


Gill-T

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After having enough troubles in a lifetime with a standard points distributor for my 305 GM block OMC, I had the points removed and an electronic ignition system put in. OMC’s are known for their difficulty to convert. The conversion was great in terms engine performance but the electronic shift assist would not work post conversion due to the non-triggering of a reduction in RPM’s when shifting gears from drive to neutral. I had to turn off the engine coming into dock because you could not move the shifter out of gear. After doing some research on this problem with OMC I found CDI makes a ESA module to help with the problem. After the mechanic placed the module, the shifting problem was solved. Boat works great, shifts great.  However, I found a new gremlin. Whenever I use an accessory that draws power ie. my downriggers or sustained raising or lowering the motor, the engine cuts out. It would appear that since the ESA module was placed, there is too much resistance to the coil and the coil is losing needed power. Does anyone have any experience with this OMC phenomenon?  The mechanic working on my boat does a lot of head scratching lol. Thanks in advance. 

Edited by Gill-T
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Might be easier to install a dedicated deep cycle battery with a isolator so that it will charge off your engine but not discharge the starting battery if the engine is off. I have converted a few and now go with a new electronic distributor that eliminates points and the Thunderbolt ignition module or whatever your wired in to  Same price as petronix but IMHO a better set up and a new distributor to boot. Best price I could find for a used module was 150.00 , paid 120.00 for updated distributor and pitched the Thunderbolt module.

 Is your engine idling higher now ? I wonder if you couldn't put in a Mercruiser momentary kill switch that they use for there older models. I am sure you could fabricate a bracket by your shift mechanism that would hold the switch and work off something moving the shifter ( not familiar with OMC outdrives ).

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  • 3 months later...

The draw from your riggers are causing the RPMs to dip and probably stalling the motor. I found in My OMC 4.3 it was difficult shifting. the RPMs have to be way low for it to shift properly. I ended up eliminating the OMC ignition ag getting a GM electronic ignition and coil. taking out the electronic shift module and just using a microswitch to blip the coil. I eventually abandoned the OMC and converted to alpha one drive. problem solved! This season i will be removing All OMC stern drive and replacing with Alpha 1 Gen2 unit. I will be placing the OMC to Alpha  conversion kit up for sale in Spring

 

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The CDI module solved the problem. Boat was running perfect at the end of season. It turns out the mechanic that was trying to adjust the shifter to solve the problem prior putting in the new CDI module, boogered up the OMC ESA module so bad it was falling apart. Any vibration or drop in voltage would stumble the engine. Frustrating when it is a mechanic creating problems instead of fixing. Glad it is done. Through it all, still caught fish lol. 

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