Yamaha E60 power issue HELP please!!

[Marcos g]

Hi everyone this is my first post here.
I've bought a boat with an Enduro 60 from 93, is an international version, according to my research is the the same as the north american version. the engine starts really good and easy usually third pull. but after running for a while (could be 10 minutes, could be 2 minutes, could half an hour) the power starts to go up and down. I did all I could think it could help but no luck yet. I've cleaned the carburetors (all 3) changed the spark plugs, spark plug cables, clean all the contacts in the ignition coils, etc... it doesn't get any better. it keeps running but no improvement.

here is a link of the motor failing. when is at high rev is when is running properly.

thanks in advance this is driving me nuts!

Marcos

[TownsendsFJR1300]

Sure sounds like an electrical issue..(Loosing spark on/off)..

[99yam40]

I had a high speed miss on my C40 that I eventually found out came from the a previous owner had drilled out the main jets.( trying to turn it into a 50 I guess)
I bought and installed new main jets and it fixed my problem.

I am not saying that is your problem, but just saying that too rich on fuel can cause missing also.

might want to check your fuel pump to make sure it is not leaking into #3 crankcase causing overly rich condition

also check to make sure the rubber plugs over the pilot(idle)jets inside the carb bowls are in place ,
if both pilot and main jets are sucking fuel out of the bowl at high RPM it might cause a rich condition.
the plug is there to force all fuel to run thru the main jet

[Marcos g]

Thanks!! ill have a look in the next couple days, the fuel pump is something I didn't play with too much.