115 mercury outboard 1984 losing power

[backlash49]

Motor runs fine for the first 10 mins. 5200 rpm, then drops to 4500 rpm, acts like losing one cyc. Take it out the next day and it does the same thing. would stator or trigger do this. all ready changed switch boxs. thanks for any help i can get. ?????

 

[canoemang]

Re: 115 mercury outboard 1984 losing power

My 86 115 would go from 5400 to 4600 rpm, i was dropping my #2 cylinder. I would let it sit and cool down then it was fine for another 5 - 10 minutes. I had shaved bits of aluminum on my #2 spark plug. The shop is rebuilding it today (under warranty still!!).


Check out your plugs and do a compression test and verify spark.

 

[backlash49]

Re: 115 mercury outboard 1984 losing power

checked compression all cyc, good 125, checked spark ok, no. 2 cyc is the one i think has the problem has alum. from piston on spark plug, but compression is good ???

 

[canoemang]

Re: 115 mercury outboard 1984 losing power

checked compression all cyc, good 125, checked spark ok, no. 2 cyc is the one i think has the problem has alum. from piston on spark plug, but compression is good ???

Maybe because it is cold you have good comp on all 6, metal tends to exand when warm/hot.. maybe it loses compression when it is warm.

hopefully someone with more knowledge will jump in and verify..

 

[backlash49]

Re: 115 mercury outboard 1984 losing power

Does anyone know what causes a cyc to run lean my #2 cyc is tiring to burn a hole in the piston still have good compression but there is some alum. on the spark plug. and you can see a pc of alum. on the piston that has burn off ?????? thanks for any help that i can get.Would like to know what causes this.