1986 Evinrude 120hp V4 Skipping at high rpm

soupie21

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Aug 4, 2013
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4
I have a 86 evinrude 120hp v4

Starts fine ,Idles fine but is shutting of intermittently at high rpms (3/4 throttle up)
It did this once then was fine next trip,and has gotten worse over the last few outings....now it does it ever time you go WOT
It does not stop completly or act like a fuel issue....it acts like you have shut the key off and back on very fast....I do hear some noise or rattle in the motor if I keep the throttle up for a bit when it does this..
I am wondering if it is a power pack issue or a rec/regulator issue or possibly something else...
I have been through the fuel system and replaced bulb,hose and clamps primer is solid when it acts up....
I have tested the coils and checked plugs for spark that all checks out....
Just wanting some ideas of where to go next...thanks
 

TrueNorthist

Petty Officer 1st Class
Joined
May 16, 2012
Messages
229
Re: 1986 Evinrude 120hp V4 Skipping at high rpm

Might be the key switch or the kill switch or something along the way. Typically the power pack etc will simply quit but who knows. Try running it with the kill wire disconnected.

edit: I see Daviet is around. He might have some better suggestions.
 

Daviet

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Sep 24, 2008
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8,958
Re: 1986 Evinrude 120hp V4 Skipping at high rpm

Use an inductive timing light and check each plug wire and see if one of them is dropping spark under load.
If you find a plug wire dropping spark, remove the coil for that cylinder and make sure the contact area to the block is clean and the bolts are tight. Might not be a bad idea to check all the connections for all the coils.
 

soupie21

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Aug 4, 2013
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Re: 1986 Evinrude 120hp V4 Skipping at high rpm

I will give the light a try, I think I will put the muffs on and see if it does it out of the water as well...One other thing I noticed is the powerpack had recently been replaced, just bought boat/motor a couple months ago had it out 20+ times and it ran great first 15.....the previous owner said the marine shop had replaced something electrical and the power pack appears to be it, all other wiring looks old...hope this info helps....
 

soupie21

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Aug 4, 2013
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Re: 1986 Evinrude 120hp V4 Skipping at high rpm

Well I stopped by and picked up some new plugs today and pulled the old ones....after inspecting them (old) they have some carbon buildup and are gapped at the least 0.80 and well out of specs...gapped the new set to 0.40 and installed then took the boat out....ran excellent...I am hoping that it was just a fouled plug or two and seems to be at this point...on the bright side I learned alot about my motor so I will be better prepared for maintenance issues in the future....thanks for the help fellas

Soup
 

Daviet

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Joined
Sep 24, 2008
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8,958
Re: 1986 Evinrude 120hp V4 Skipping at high rpm

Glad you got it figured out.
Sometimes the checking the simple stuff first saves a lot of problems.
 

soupie21

Recruit
Joined
Aug 4, 2013
Messages
4
Re: 1986 Evinrude 120hp V4 Skipping at high rpm

Yeah simple and cheap... 8 bucks and some change and she is running good...took a second trip out today and no problems,so I would say that got it....thanks for the input fellas...
 
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