2000 Blue Wave 18ft. 99 Johnson 115hp. Boat is running rough at idle and had to actually keep choke pushed in to get to going. Once it gets going runs ok. The kill switch lanyard i noticed was falling off and it actually ran across the lake without it. I put it on and when you turn key it falls off. This i can replace no problem.
I am wondering if this might be what is causing the misfire. It started after owner (I get to work on it and borrow) ran full throttle about a mile and then went down to idle. The lanyard had fell off a couple times then but i was not at the wheel so i didn't know at the time. I have changed Fuel Filter, Plugs, and fuel line from connector going into motor to fuel filter and there to carb. I will replace kill switch, but just if anyone knows will it cause boat to run like not getting enough gas,fire?? Never had any problems at all this started all at once. Is there a way to check this to see if it is actually the kill switch? Oh by the way it is my Lake Rangers boat lol. He is my neighbor and a heck of a good man. Sorry so long on this. Thanks also for any help.

sounds to me like you have a bad fuel pump or an air leak in the line to the engine.
you also need to fix the kill switch if by lanyard falls off you mean it disconnects, if so it has been disconnected and is not working at all.

this

or carb need cleaned

my 175 johnson did the same thing, that is when the electric pump went in, combo of bad pump and I screwed up and had an air leak at the engine connection too.

I know someone that has a electric pump cheap too lol

If it is the lanyard that goes on key switch it will run without it on it does not work like yamaha and merc it actually turns the key off put your key in run pos and pull it then check were your key is it will be off

Have the cylinder head "O" ring seals replaced. Have had several start leaking water causing the bad running and if you run it too long it will get a piston. PS: Kill switch will kill all fire to all cylinders.

The lanyard problem i think is it is just wore out where it is supposed to fit. That is not a big deal. The misfire is what really concerns me. Thought is being loose might be letting it jump fire or something, making it misfire,
Is there anyway to check for an air leak in the line under the deck? Also the bulb never seems to stay hard after puming it up. Actually it never gets really what you call firm when pumping it unless the tank is full. I have told owner that i thought there might be an air leak somewhere. Thats why i changed a bit of hose that had weather looking cracks in it. Also will regular fuel line from local parts store be good enough fuel? Anyway fella's thanks for all the ideas, and thanks to anyone that gives an idea. Someone might have had just this problem as many boat people on here i am sure there is. And just maybe they will stumble across this post lol.

Easy thing is to 1st fix the simple kill switch circuit. It is inoperable and can be placing a direct momentary ground on the very power circuit that builds the voltages to fire the spark plugs. if it glitches with a brief momentary contact, the motor would misfire with no spark, just like it is supposed to.

yes you can use auto fuel line, I have had it on my champion for over 3 yrs now and no problems.

Tahnsk for the replys fella's I replaced the ignition switch this morn.
Boat cranks up good. Then when put in gear and given fuel it dies or if it stays running it is real rough. I tried using a test lite in the spark plug boot to see if i could tell which cyl. it was missing on but must not have had a good ground or it happend to hit on that cyl. when i was testing. I know grounding it should change motor a little as on a vechicle. I don't have the $$ to take it to a shop at this time. And it is not my boat. Was told by mech. today that they have something on the motor that even if sucking some air it keeps the bowls on the carb full. He also said it probabaly has sucked something from hose innerliner to trash in tank into one of the jets. Also said the carbs are real tricky and i should not attempt. lol He knows me

You need to get a spark tester and make sure all cylinders are firing.

This is what i was doing Todd. You can do the same with a test light. Ground it to motor and stick in spark boot, if it changed sound it is firing. If not it is not firing.
This boat runs smooth a sec or two then has miss a sec or two. Kinda hits hard when it misfires. Pulled the plugs again and they looked fine. None were wet. All getting a slight chocolate brown tint to them. But they are brand new so hard to tell alot from them yet. Lake is low here so only a few ramps open and hard to block one long enough to really research much. I tried makeing a water pit but not sure that getting enough water thru so will wait till i can get the motor submerged. I wonder if the oiler (self oiling) is not putting enough or maybe to much. I also noticed after all this that the fuel line looked not have been pushed up on the dealy at the motor all the way. Don't know if it was like that or not. I think i would have noticed this. I have been checking the line for cracks though so i may have pulled it loose a little. Anyway i am going to take it this morning to ramp and see what i can find. Again thanks to everyone for posting and no post goes unread or none are not concidered as a possibility. Any other ideas will also be looked at and if i figure it out without taking to shop I will let you all know how what and where lol.

Well changed all but the main fuel line running from tank to bulb. It is run thru the deck so i really didn't figure it would be weather cracked or injured in anyway. I did however recieve word that the ethenol that we are forced to use could have broken down the inner linings causeing the fuel line to suck together slowing down fuel. This thing will crank fine but misses it also misses at an idle in gear but will stay running. When you give it throttle it will pick up for a sec. then die. I can start giving throttle and push choke in it will pick on up and have to keep pushing choke in and out until about 1/2 throttle and it will take off from there and seems to run ok. Top end speed is what it should be. When you slow down and not full throttle it goes to missing again. I can slow down and ease up to anchor and it will run but misses. Have to repeat process to return. But no problem starting. Think the main line has gotten bad????? All other lines have been replaced.