Misfiring?

[71whaler]

I have a 1983 Evinrude, 75HP. Model E75TRLCTE. <br /><br />When I first bought the boat, last May, I had the carbs rebuilt and the mechanic mentioned that the motor had an occasional misfire but that this would be difficult to diagnose. I have since used the boat 1-2X week with no major problems. However on the last trip back to the dock, I noticed that 3X the noise from the motor changed and it seemed that the RPMS dropped, no tach, and my speed dropped. Each time it only lasted for 30 seconds or so and then caught back up. This was at no wake speed. It has done this occassionally before but never 3X right in a row. Recently I have purchased a Seloc manual and just yesterday ordered an original OMC shop manual. Any suggestions?

 

[JB]

Re: Misfiring?

Ahoy, Whaler.<br /><br />Look for a sticking float or loose debris in one carb. <br /><br />Another possibility is one carb running a tiny bit rich from the low speed jet putting that cylinder into a 4 cycling mode once in a while.<br /><br />Good luck.

 

[71whaler]

Re: Misfiring?

Thanks JB. I'll let you know how I make out.

 

[R.Johnson]

Re: Misfiring?

This also sounds like you could have a ignition failure to one cylinder when the engine goes in, and out like this, a sensor, coil, or simply a spark plug.