Evinrude 235 Problem

Hello, I’m hoping you can help me, I have a 235 Evinrude it runs well aside from a slight miss when the motor is at 1500 rpm the miss occurs about every 5 seconds followed with a puff of smoke out the exhaust which tells me it is a spark misfire. I just changed the plugs.  The gas is over a year old. Could I have a weak coil? What resistance should I read across the windings?  Thank you so much for you help.  Jason

Jason:

From the description of your problem, it sounds more like this is the transition from the low speed circuit in the carb to the intermediate and high speed circuits. This engine was famous for "four stroking" during this phase. This will appear like a misfire. Sometimes a change in propeller size will cause this phenomenon to occur at a different RPM. Usually an ignition problem doesn't just doesn't come and go on the old OMC's that I have worked with. Usually if you have an ignition problem, it is very obvious. And 9 times out of 10, it is the power pack itself and not the coil. Most of the coil problems I have seen come from erosion on the coil wires themselves. Water drips in from the hood vent directly onto the coils on the back of the motor. Check all of your wires, connections and boots. Hope this helps out.

Randy

Please submit whatever questions you have to IHRTechTalk@yahoo.com.  All questions and answers selected will be displayed on this page as they come in.  Note: though all boaters are welcome, priority may be given to I.H.R. members.  Randy can not be held responsible for any advice given.  Though his information and expertise is second to none, he has no control over what you do with your boat.  It is up to you to boat safely and act responsibly, and his advice is only to be used as a guidance for your high performance boat/motor of which you are the one responsible for the risks involved.

Thanks,
Mark C.

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