1993 evinrude reduces rpms after warmup

ottersea

Recruit
Joined
Feb 2, 2015
Messages
3
I have a '93 70 hp evinrude 2 stroke. It starts/runs well but after running for about 10 minutes the rpms/ power drops of to apporx. 1/3 max. In the past the rpms often picked back up after about 10 minutes. It no longer seems to be doing so.This problem has been intermittent but is becoming more regular. After sitting overnight the engine always starts and runs well for at least 10 min. the following morning (and sometimes the issue will not evidence itself at all.) Thanks for any ideas or further questions you might have.
 

Bosunsmate

Admiral
Joined
Apr 7, 2012
Messages
6,129
When engines heat up weak electrical components start to fail.
Use a spark tester or a timing light to try and track it down to specific cylinders/sparkplugs not firing.
You can also use a digitial multimeter to do some basic resistance tests on the stator and timing base.
Also look over the coils (by the sparkplugs) for cracking
 

WernerF

Petty Officer 1st Class
Joined
Sep 5, 2011
Messages
320
Had the same issue on my 1989 60hp a few years ago. It turned out to be the rev limiter inside the powerpack. But do not throw parts on your motor without testing. As Bosunsmate said, first find out that your ignition fails.
 
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