Evinrude 40 hp 1986 - loss of power

Hi!
I?ve been reading this forum the last couple of days looking for a similar problem that I have, and found some clues to work with. But the threads stops before the problem is solved so its difficult to know which lead I should follow.
I have a 1986 european buildt (Belgium) Evinrude 40 hp that don?t work very good anymore.
It all started at the end of the last season when the engine began to misfire and loose power at medium and high speed. After a while I had problems to get it to plane - sometimes it did, sometimes not.
I?ve only had the engine for one season and it worked just fine untill this happened. I thought maybee it didn?t get enough fuel so I checked the fuelline from the gas tank to the carbs. To my surprise I found out that a previous owner had glued a large crack in the fuelpump-housing with epoxy glue. The glued part more or less fell off the rest of the fuelpump when I took it apart. I was satisfied when I thought I had found the problem and stored the engine i my garage for the winter.
A couple of weeks ago, I put in a new fuelpump, new sparkplugs, a new fueltank/fuel and fuelhose and bought a Seloc manual. Then I drove off to the sea to test the rig.
Nothing had changed. The engine startet and it sounded fine at idle, but was still misfiring at load. The strange thing is that it works better when I get it to plane, and I?m also able to keep it there. But it still misfires.
I went back home with the lot and cleaned the carbs with carbcleaner, blew all the jets with compressed air but nothing changed. Still the same problem.
No I started to suspect that the problem was something else than fuelproblems.
I made a compressiontest and both cyls gave 120 psi. I checked the spark and it looked good when I crancked the engine. I checked the coils for visible cracks and wear on the contactpoints. I found that the connecting point for the cable between the lower coil and a "black sealed box" at the left side of the engine was corroded. The point was actually reduced with 10-15 % compared to the other coil. I cleaned it, ensured that the cable had a good connection, but I have not tested the result yet.
So ladies and gents - before I tow the lot back to the sea for another test, is it anything else I can do/test? Do you think that a corroded contactpoint on one of the coils can produce this error?
Thanks a lot for a brilliant forum!
All the best from

Paul

Re: Evinrude 40 hp 1986 - loss of power

Not sure what the contact point is you are talking about but any dirty/corroded,loose connection could surely cause trouble.Be sure all wires are not worn anywhere, loose, cracked or rubbing on anything.Don't do any trouble shooting without a manual as you could damage the ignition system.
Look at the plugs I think you may find one is blacker and wetter than the other.Sometimes a plug will fail prematurely.Plugs are normally brownish to lighty black,unless you run a lot at no wake speeds.Sometimes a plug will fire in a test and not fire under compression.

Re: Evinrude 40 hp 1986 - loss of power

Hi and thanks for your answer!
I?m not into the details on this subject, but the cable/electric leader I am refering to is not the sparkplug leader from the coil. It is another much thinner leader/wire which is connected to the lower coil on one side and to a black completely sealed "black box" (power pack?) on the other side. The upper coil has the same leader, but the contact points looks much better. I don?t think it is possible to replace the leaders. It appear to be sealed off inside the "black box". I guess it?s the electric leader from the ignition system to the coil?
I?ve just changed the sparkplugs and they look just like you said - brownish to light black on both cyls. But if you suggest it is neccesary to replace them one more time to be sure, I will do it.
I guess I?ve drive down to the sea tomorrow to do another test under load after the cleaning of the contact points/leaders - if the car works. My wife just called me and told that it is a funny squeeling sound from the car -probably from the gearbox. Just what I needed!!

Thanks again,
Paul