I am about at the end of what I know. So I need some help.
Motor - 115 johnson 1991.
Recent Repairs - spark plugs, water jacket gasket, choke cover plate.
Problem - I have had this problem for a couple months. I thought the water jacket repair would fix it.(The water jacket was spraying water on a spark plug), but it did not.
The motor seems to start OK. When the motor is cold and idles, every couple of second or so, it misses. When the motor warms up, it will not hardly start. When I try to go forward, the motor will only go to around 2K RPMs and sounds like it is boging down. The motor seems like it has more power as half throttle than full. I have also noticed a lot of black oil coming from the prop. This is from unburnt gas (also see it when it is in the water). I think it is the carbs, but not sure. Any suggestions?
Thanks,
Chris

You are probably right about the carbs... How long has it been since they were cleaned and rebuilt???? If you can do a compression test first to rule out a more serious problem do that..The black oil is unburned fuel and oil draining out the exhaust and is normal...Do a decarb on the engine then rebuild carbs and new champion plugs, the right #, Make sure you get the sync&link set right when you put it back together... You might also call Spanky if it's more than you want to try..

It sounds to me like he is dropping a cylinder or two on spark. This could be from a low power stator, ignition box dying, or a trigger dropping one pick-up. The other thing that could cause this could be a bad diaphram in the fuel pump. The VRO, if your using it, or fuel pump may be putting gas into the block via the pulseateing line. When ever you drop spark, it floods those cylinders and here's the black oil goo. I would take an inductive timing light and while ideling go from plug to plug and see if the timeing light picks up a signal. If the spark plug is not firing in that hole, the timeing light will not flash. (cheep way to test) The spark plug may fire outside the cylinder but not under compression.

Yeah, it could also be anything Mike said..He is a pro tech and makes his living fixing boat engines....It sounds like its time for an overall check up...Top to bottom... Good luck and hope you get it going...

pm sent

Thank you. It does sound like a dropped cylinder. It started very sudden. I will do the timing light trick test and report back.

Thanks again,
Chris

MartinPro. I got you PM. I may be contacting you in the next couple of weeks.

i got mine in the mud down at port a. it got hot and set off the buzzer. i got the water pumping again.afterwards it wouldnt run over 2k rpms and was cutting out. i never killed it because we were a ways from the ramp. later on i found out it had gone into safe mode and wouldnt run over 2k.all i needed to do was kill it and restart after cooling. i took it back out and it ran fine afterwards. just wondering if yours has stuck in "safe mode" somehow. mine is a 95 model though. not sure if yours is set up the same.

Mine did the same thing and it was the Power Pack.

some times to diagnos a bad pack it is as easy as lightly tapping it and see if the running changes (gets better then worse)

"...The spark plug may fire outside the cylinder but not under compression..."

It's good to hear you say that Mike. I have argued with people for years over that very subject. Had it happen more than once on Yamaha race bikes. You are one of the few people outside of my family that has ever mentioned that.

"You velly smart guy".

I would also let it idle a bit and pull the plugs, inspecting them for water. One tiny droplet on a plug will tell you if you have a headgasket ( or worse) problem that might have been overlooked.

Yes to all of the above but had a 90hp acting like this and found the anti-syphon valve was restricting the fuel and a 1992 Cajun with a 115 that had a fuel selector with a main and auxiliary position that the plastic fuel valve was bad restricting the fuel. Both of these the fuel bulb would`nt pump up firm and was slow to fill back with fuel after squeezing. have also been seeing a lot of fuel line problems from ethynol.

I do not have the VRO. I will give the "light tap" trick a try also. Now I think about it, this started very quickly. I was running across galveston bay, and it started. Then a couple seconds later, ran right. Than a couple seconds later, ran bad. Not it just runs bad. I will also try all of the connections to make sure something is not loose or got a little corrosion on it.

Do you have a water separator ? Checked your fuel tank for water yet? Just throwing out ideas here.

no water seperator, but that will be my next buy.

I purchased a new powerpack today. Mallary, I hope it is a good brand.

I was getting weak fire to the left bank of pistons. I moved coils around and had the same results, left bank of pistons not firing.

I also got a new set of plug wires just for good measure.. If this does not work, Rockwall Marine, here I come.