1980s evinrude 40 hp power loss

[Neil]

Well like post says i have a 80s 40 hp evinrude. Ive had the boat several years with no pronlems. The auto oiler was disconnected a few years ago, just incase. The motor otherwise hasnt been touched. Ive had the boat out twice this year and ran great. Well last night i left the launch ramp only went 1/4 mile running WOT and all of a sudden the motor just brrr like i had dropped throttle to around 2000 rpm. All linkage looks ok , even starting you have to move throttle halfway just to idle, idle and runs smooth , will rev up with no load. But just low power in gear.

 

[Neil]

Ok so i checked compression 135,140 for the twin. I changed fuel filter wasnt clogged but changed anyway. I checked the plugs one was firing from plug body to ground instead of threw electrode. I replaced both plugs will try it out tonight

 

[Neil]

Apperentlu plu was the problem runs great now

 

[nccatfisher]

Gotta love an easy fix.