88 evinrude 120 loses power under WOT

[dynatrak94]

first off i did my fair share of searching and i couldnt find anything that was persistent like my situation was, so just preapologizing if it seems like another story. i have an 88 evinrude 120 looper motor and took it to the lake over the past few weekends, idles fine and boat will shoot out of the hole no problem run about 100 yards and the motor will drop from 5500 to 3200-3800 will rev back and forth between the two for a minute and eventually bog down like it is running on two cylinders. i can cut it off or let it sit for a minute and it will plane out but the problem persists again. i check compression, everything seems ok, and fuel is fresh with new filter. i pulled the plugs and they look wet as if they were not firing. also i disconnected the temp switches thinking it might have to do with a cooling problem but it still does the same thing. it appears the powerpack has been replaced but no way of knowing for sure. i have done a fair share of research and everyone refers to powerpacks and coils breaking down once they warm up or get hot. just want to know if anyone might have had the same problem, any info would be much appreciated and useful, thanks.

 

[tashasdaddy]

Re: 88 evinrude 120 loses power under WOT

vent open on the fuel tank? does the fuel bulb go flat?

 

[dynatrak94]

Re: 88 evinrude 120 loses power under WOT

the vent is open and the bulb does not go flat. i ran it in the driveway today and pulled the plugs on it. the top plugs on bank 1 and 2 looked burned as if they were sparking. one of the bottom plugs looked like it was somewhat wet and the other one looked really wet. i also checked all the jets in the carbs and they are clean and can blow fine through them. i know my fuel mixture is correct and i know the compression is ok. i put a spark tester between the wires and plugs and it has a spark. i thought the spark would be stronger but i have nothing to compare to. i mean it is definately weaker than my 94 chevy silverado but i dont know how strong the spark needs to be on outboards. also i forgot to say that eventually after trying to get the boat to move on plane it will cut off and play hell to start again, almost like the plugs are fouled. can change plugs in the motor and it will do the whole process over again from the beginning.