60 hp Mariner losing power

[riverebel]

I have a 60 hp Mariner og381643 that runs like new for about 45 minutes at any RPM.It will slowly start losing RPM's till it drops to 3000 & will run all day at that.I have pretty much eliminated it as a fuel problem.After you let it sit for awhile it is ok for another 45 minutes or so.Is their something that could be heating up & breaking down to cause this.Would the high speed part of the stator cause this or would it go all at once.<br /> thanks

 

[riverebel]

Re: 60 hp Mariner losing power

^

 

[riverebel]

Re: 60 hp Mariner losing power

come on now....I know at least 1 of you Mercury guru's have had this problem before

 

[Bomber13]

Re: 60 hp Mariner losing power

I have had a similar problem before on my Mercury 60 hp and it was a bad insulator on a wire but I have also had the exact problem on another type of high performance 2-stroke engine.<br /> You could have a week spot on a wire insulator but my first thought is that you are running it lean at high RPM's. You may be slightly rich at lower RPM's but have your high end set too lean. I have experienced 2-strokes be set rich on the low end and lean on the high end. What happens is at the lower end, fuel/air mix can build up in the lower end and as the RPM's come up, the excess is neutralized until it becomes lean on the high end. A 2-stroke that is run lean will build up excess heat after some time (The amount of time depends on how lean). Judging from what you said, something is getting hot.<br />Also, check all the wires in the ignition system for cracks.<br />As for the stator, in my experience with 2-strokes, if the stator goes bad it is fairly consistent on acting up (Meaning not just when warm). BE SYSTAMATIC IN YOUR APPROACH <br />GOOD LUCK<br />

 

[2springers26]

Re: 60 hp Mariner losing power

i'd be looking @ the stator... the 3000 rpm's points to that.. try a heat gun on the stator & test it out..... sound like heat is giving you issues....

 

[riverebel]

Re: 60 hp Mariner losing power

this motor had a stator put in just before i bought it last year,not saying that it aint bad too.when you say a bad insulator,are you referring to the wire coating?I tried it without the cowling too.same results.was overcharging & replaced regulator/rectifier.same results.its kinda hard to check it out because its on a pontoon that is in water all season.I could probably replace the stator for what it costs to get it pulled out & brought home.would the switchbox or trigger have symtoms like this? this motor has less than 100 hours on it

 

[riverebel]

Re: 60 hp Mariner losing power

bump

 

[riverebel]

Re: 60 hp Mariner losing power

bump

 

[Bomber13]

Re: 60 hp Mariner losing power

Yes, I am refering to the coating on the wire. As current is running through electrical wires a certain amount of heat does build up causing expansion. When the enigine is cold and not running. check wires for cracks. You might even look for a thin spot in a wire. This could be a weak spot in the wire. As I mentioned, when the wire warms up, the insulation expands and will actually start to seperate the strands of the wire if there is a weak spot.<br />Also, you still want to check the stator as "2springer26" mentioned. You should do this first as it will take awhile to go through the ignition wires.