Mercury 15HP 2-stroke dying a slow death

[Todtc]

Hi All,

I have never been steered wrong here and hope to keep my streak alive! My early 90's Mercury 2-stroke 15HP duck boat motor is slowly dying. I had it serviced by a Mercury dealer last year when the stator went out and I couldn't get it started. It has run great this hunting year (since October) but a couple weeks ago it died on initial start and was tough to get going again.

It ran fine that day, but the next morning, after starting fine, it ran very rough at all speeds except full throttle. Anything less and it felt as though I was losing spark momentarily and the entire engine was jump, almost like I was moving the kill switch on and off quickly.

Today, the motor started fine but idled rough. I gave it gas and got probably less than half power, even at full throttle. The plugs are new from the service last year. I use stabilized fuel and the fuel in the tank is new.

Any ideas where to start before I lug it back to the shop?

Thank you!!

 

[kabcpapc]

Re: Mercury 15HP 2-stroke dying a slow death

Even though you say the fuel is "new", I would bet that the new fuel had some water in it, maybe more than the stabilizer could handle. It happened to me once and the motor acted like yours. Try replacing the "new" fuel, add some more stabilizer and see how the motor does. If it still doesn't run right, lug it to the mechanic.

 

[Texasmark]

Re: Mercury 15HP 2-stroke dying a slow death

Also I would look herein for the "Decarb" process and accomplish it. Then keep Sea Foam in your gas tank (1 oz per gallon and it has no effect on your gas oil ratio....just think of it as gas even though there is some oil in it).

Let us know.

Mark