115 Merc Advice

I have a 2002 Merc 115 carb two stroke outboard on a Lund Mr. Pike that has an obvious miss when accelerating to get on plane. Once on plane not so obvious. Greater the load such as pulling a tube the more obvious the miss is. Once on plane this miss will disappear after running about 2 minutes and not to come back rest of day. Next morning, miss is back. But every time I have taken it out this summer same thing, and this fall once the weather turned cold it would take more time running on plane before miss would stop. But it does stop and then runs great. Starts fine. I have already tried multiple bottles of Sea-Foam and new plugs and wires.

I have taken this motor to a local merc dealer where I was charged $240 to hear they could find nothing wrong and do not want to repeat that experience. I was told the compression was very good and no water in gas. If this motor has an electrical ignition problem I would think the respective components could be tested with a meter.

Any advice? thanks

Have the carbs been PROPERLY cleaned in the last 3-5 years? And if so how does the fuel system get drained each year?

Thermostat tested or replaced?

I had a problem with my merc which was similar.
I had the coils replaced and it runs fine.

Good luck.

Marmike beat me to it. Coils. Get them checked out. That’s where I’d start looking.

CDI pack(s) could be a possible culprit as well, but I’d look at coils first.

Misses are almost never fuel related. If the engine is gettig enough fuel to run, it’s not going to be missing. Bogging down is often fuel ratled, but a stuttering miss is not likely to be fuel.

Grouse

I am having this same issue with my 115 merc, although it is a older model, it wants to get up and go but just dosn’t as this just started this fall. I did have the CDI power packs replaced a couple years back and will pull the carbs and clean them out this spring.

My question is for marmike and grouse, could you elaberate a little more on these coils as I am not familar with those and it sound like that could be my problem.

Thanks, Wahly

had to have all coils replaced on my 2008, although mine would not get up on plane and go it would just put along in “safe mode”. I was lucky mine was under warranty so no idea on cost.

If you do some searching, you will see that Mercury has a testing procedure for testing the electrical system. You can do all the tests with an ohm meter. I do agree that it is electrical. You can also Google your problem. Sometimes you will find your answers this way, also see if You Tube might have a video on checking the system. I’m not saying You Tube will, just saying it might.