Elusive 25hp Evinrude Problem

[alumacraft74]

New to site ,hope ya'll can help.Ihave a "74 Evinrude 25hp #25402.I have had this problem since I purchased a year ago.I can put the boat in the lake,start it up,runs great.I can idle all day,but as soon as I go wide open throttle,which runs fine always at wot,and try to idle back down such as coming to shore or ramp it starts dropping a cylinder.I can go back to WOT and its fine but when I try to idle it loses a cylinder and eventually both because it dies,and wont start back.Let it sit 30min to 1 hr. and it will start right up and idle.I have totally rebuilt carb several times(soak overnite and blow passages with air hose),New coils on both cylinders,plugs,Points and condensor gapped at .020,and new Driver coil.Always the same problem and cant figure what it is.I would greatly appreciate anyone with some suggestions. Thanks, Chad PS. Compression 120# in both cylinders

 

[F_R]

Re: Elusive 25hp Evinrude Problem

Next time it dies and won't restart, check the spark. At least narrow it down to one system or another.

 

[Bobobob]

Re: Elusive 25hp Evinrude Problem

Sounds like the coils are heating up.

 

[Bindernut]

Re: Elusive 25hp Evinrude Problem

Sounds like the coils are heating up.

That would be my guess too. Had a 69 25hp that did a similar thing last summer, granted it still had the under-the-flywheel coil setup instead of the ones mounted on the jugs like yours but the symptoms were the same as you're describing.

You said you've replaced both coils and darn near everything else...how about checking the wires that come from the mag plate to the coils. You might have a broken wire giving you an intermittent when you open/close the throttle and/or under hot/cold conditions.

 

[tashasdaddy]

Re: Elusive 25hp Evinrude Problem

it could also be flooding out, the carb linkage out of adjustment with the spark, getting too much gas. check link N sinc. i would think if the coils are breaking down, it would do it on a long run also.

 

[alumacraft74]

Re: Elusive 25hp Evinrude Problem

thanks guys, both coils are new and it isnt the same cylinder every time.I checked spark when it does it and not the same cylinder every time.I've done link/sync and checked all wires to and from driver coil.They look fine.I'm stumped! It's not flooding out either.If you can keep it running after coming off of full throttle ,which takes forever it will eventually run right.??????????I'm fixing to make a boat anchor out of it. One other thing is when motor warms up there is a slight leak on the port side and between cranckcase.Its oil and it just barely bubbles,if that makes sense. Any ideas? Could that leak be a factor...... Thanks , Chad

 

[tashasdaddy]

Re: Elusive 25hp Evinrude Problem

you just found your problem. hate when we don't get the whole story.

 

[alumacraft74]

Re: Elusive 25hp Evinrude Problem

sorry bout leaving that out!So thats my problem.Fix the leak and that fixes the problem? Thanks for all the help guys,guess I'll get a gasket set.