25 hp merc problems

[toocheaptosmoke]

I have a 25 hp. merc that is a 1994 i believe. the motor has always started fairly easy and has good power. one problem is, it hesitates when you try to get going from a slow speed. after a couple seconds the power kicks in and it takes off. it doesn't bog, it just doesn't want to go. another problem i noticed is the plugs are different colors. the bottom runs very clean, almost too clean for my liking, but the electrode doesn't look like it's running lean. the top is always dark brown to black. i did a compression test and both cylinders are the same, the top might have a pound or two more. another thing i noticed yesterday is a high idle after a good run. i have experience with quad and snowmobile engines but outboards i'm not as familiar with, so I appreciate any help.

 

[WillyBWright]

Re: 25 hp merc problems

You're not getting spark to the clean sparkplug. Could be the coil, but more likely to be the switchbox. Don't buy anything without first checking for spark. There is only one carb, so the only way the motor could run lean is if both were lean or the one cylinder had no compression (to speak of). But even that would leave deopsits. Lack of deposits almost always means no spark.

 

[toocheaptosmoke]

Re: 25 hp merc problems

alright, a loss of spark on that cylinder would explain the plug color and the way it runs sometimes. is the "switchbox" like a cdi? any way of testing it? i'll check the spark on the lower cylinder today and make sure all the grounds and connections are clean. thanks for the help.

 

[toocheaptosmoke]

Re: 25 hp merc problems

I went through most of the wires between the switch box and the coils, all looked good. i switched coils and the bottom cylinder still does the same thing. i checked for spark, both cylinders are getting some spark but neither looks real healthy. i haven't checked the wiring between the switch box and the stator yet. any other possible problems? i don't want to buy a switchbox until i'm positive that's the pronlem. thanks