Dedicated To The Smallest Of Skiffs banner

1 - 15 of 15 Posts

·
I Love microskiff.com!
Joined
·
16 Posts
Discussion Starter #1
I have a new to me 25 mariner mid 90's that my father in law gave me. First off it is not in the best of shape, but I had it running great. Took it out for my first real run and it ran perfectly for about an hour then cut power by about half, wouldn't plane and ran like crap. Got home and tore into it looking for an electrical problem (felt like only one cylinder firing) and found a bad coil. The magnet and grounding strap had broken. So i replaced both coils and took it to the water today. It was much easier to start and idled pretty good, but not as good as before the power loss. Anyway as soon as I hit the throttle it started back running rough and would barely make any power. I have recently cleaned out the carb and replaced the plugs, but have done nothing with the fuel pump diaphram. I do not think it is a fuel issue, I believe it is electrical. Does anyone have any Ideas of where to help me get started.
Thanks,
Maclin
 

·
I Love microskiff.com!
Joined
·
217 Posts
while running the the engine in gear and full throttle pump the fuel bulb if it picks up speed and runs better its most likely the fuel pump you can also try this while idling
 

·
I Love microskiff.com!
Joined
·
114 Posts
Could be going into engine slowdown mode due to overheating, or engine oil sensor. This will exibit itself as smooth idle, easy start, and running real bad if you give it throttle. Same symptom as hitting the rev limiter at WOT.

Bob
 

·
Administrator
Joined
·
5,879 Posts
i had a '98 after several years of great performance , it started doing the same thing.. if possible $$$   -replace all the electrical components. i did it to mine and it ran perfect again for many years,,
-i think some of the parts were called :
     -trigger
     -coils
    -brain ?
   -stator
     i did this before messing with the carbs, i always ran all the gas out during the flushing process and for 12 years NEVER had a carb issue.
-compressions sound OK----
             good luck        -anytide
 

·
I Love microskiff.com!
Joined
·
2,820 Posts
Could be going into engine slowdown mode due to overheating, or engine oil sensor. This will exibit itself as smooth idle, easy start, and running real bad if you give it throttle. Same symptom as hitting the rev limiter at WOT.

Bob
i dont think this is an issure with this motor, the 2 strokes are pretty simple. sounds like a fuel issue to me, make sure you start with a clean tank, clean fresh fuel, good fuel lines preferably new :) i've had issues similar to this with 2 different merc 2 smokes and solved the problem simply by removing the carb, unscrewing a few of the little cover plates and bowl and hosing down real good with carb cleaner and now they run like a scalded dog :eek: ;D
 

·
Cert. Yamaha technician
Joined
·
4,330 Posts
Ok, heres what you do. Buy one of those 5 dollar inline spark checkers that plugs in between your sparkplug and wire, check both cylinders while the motors running and make sure both sparks look equally strong, if so its not an electrical issue. But mercury isnt best known for its "good" electrical parts ::), if its not electrical its carbureator, to me it sounds like the lowrange-idle circuit is clogged. Also check for loose or dirty grounds and connections :cool:
 

·
Registered
Joined
·
786 Posts
You can do a real quick spark check with a good insulated screwdriver. Test one coil at a time. You should have a hot blue/white spark on each. We used to make our own Home made spark tester for this job, but a screwdriver shoved inside the plug wire cap will work.

Frank_S
 

·
I Love microskiff.com!
Joined
·
16 Posts
Discussion Starter #10
Thanks for the ideas. I have not had a chance to mess with it yet, but I will be able to work on it in the next few days. I will keep ya'll updated.
Maclin
 

·
I Love microskiff.com!
Joined
·
16 Posts
Discussion Starter #11
Ok. So I think I have it narrowed down to the electrical switch. I am only getting power to one of the wires out of the switch and the other one is dead. I have tracked down the part and it appears that I am looking between $110 and $160. The only issue is that my # is 339-7452a17 and the only one I can find ends in 19. Is this the new part # or is it something else. Also how will I know which of the wires going to the coils goes where. They are both green with a yellow stripe.
Thanks,
Mclin
 

·
> PRO STAFF <
Joined
·
7,516 Posts
Parts numbers get changed. May have happened to yours.
Talk to your parts dealer and ask if this has occurred.
Wires from switch box to coils are not only color coded,
but are numbered also. Check closely.
 

·
Registered
Joined
·
4,259 Posts
Here's a photo from a running Matiner ... Green with yellow stripe goes to top coil

hope this helps ...


 

·
I Love microskiff.com!
Joined
·
16 Posts
Discussion Starter #14
Guys,
  Thanks for all the help and input.  I replaced the electrical switch and it is running like a scalded dog above idle. However, now at idle it runs rough and does not idle low like it did before the switch went out.  I am thinking the fuel pump diaphram on the side of the carb could be the problem, but am not sure.  At idle it is shaking real bad but above that it runs great.  Any ideas?

BTW I did a speed run with my GPS and got 30.2 MPH with just me and 3 gallons of gas.
Maclin
 
1 - 15 of 15 Posts
Top