1990 5hp 2stroke rough idling/misfire

[gatorman21218]

hello. I have a 1990 5hp 2stroke that I am trying to get going. 2 summers ago it spent a little time under water (Hurricane Isabel? lifted the dock box off the dock and it sank. the motor was in the box) any way the marina owner took care of it and last summer i tried to get it going but the piston had froze. i got it moving but it didnt run right. It sat in the garage untill last week I worked on it. I took apart the carb and cleaned it out. the needle looked okay, but the jets started to strip when i tried to unscrew them so i just left them alone. i also changed the spark plug, impeller, and gear oil. This weekend I took it out for a 20 min trip (avon inflatable) and it ran fine on all levels of throtle. I went in for lunch and came back and had it going full throttle on a plane when it started to miss. i throttle back and it seemed to work and i had it wide open again and it just turned off like a light switch. It then was very difficult to start and would stall on idle. I limped back home, not going more than 25% or else it would start to miss badly. at the dock i couldnt even get it to idle before it would stall. the fuel is 2 days old. should i rebuild the carb? I'm at the end of my mechanical experitice. thanks, Jim

 

[achris]

Re: 1990 5hp 2stroke rough idling/misfire

Sounds more like a wet ignition system. I had one of these engines go under on the back of a tender. I was watching a guy unload this boat from the top of the hard top of the big boat when the wind caught it and over it went. I was there is a couple of minutes and helped him right the tender. I told him I was a Merc mechanic and would help him dry it out. He said it was only under for a couple of minutes and should be ok.... 30 minutes later we got it running! The cylinder was full of water and all up under the flywheel was soaked, and that was only after a couple of minutes.

Pull the flywheel and make sure everything under there is dry and corrosion free. Check all the electrical connections and check for strong spark on all cylinders (I know there's only one. )

Chris...........

 

[gatorman21218]

Re: 1990 5hp 2stroke rough idling/misfire

thanks achris! alright I got the flywheel off (as much fun as that was I dont want to do it again any time soon) and there is a little spot rust on the underside of the flywheel and a little bit more on the driveshaft. the white thing bolted to the inside (the exciter coil???) has a good amount of rust on it. i left my multimeter at the lake but do you think that that needs to be replaced? I also looked at the connections and some of them need to be replaced. That i can handle. The coil is 40 bucks that i will reluctantly spend but not if you dont think so.

 

[achris]

Re: 1990 5hp 2stroke rough idling/misfire

Without testing the coil there is no way I can say whether it is good or not....
All electrical connection should be clean, tight and not making path to ground (unless they are designed to). Get the multimeter and start checking before replacing parts. I preference is to troubleshoot than shotgun.

Chris..............

 

[gatorman21218]

Re: 1990 5hp 2stroke rough idling/misfire

ok i got the meter (finally) and have stripped the electrical parts and are now sitting on my desk. what exactly am i looking for? the seloc manual is not a great help. the one ting i did test though is that the ignition coil is reading 3.5 ohms and the range should be 4.25-5.75.