1969 jonny 115 losing cyl at low idle?

[captainspike]

heYeveryone,my eng picked up a new bug,running crappy at low idle,will start fine and go right away,but if you stop for a few minutes and shut it off or evan sit there in idle put in gear to go and it feels like im losing a cyl,feather the throttle and she gets ups and goes like a bat outa hell,heres whats new,fuel lines with new ball,new fuel filter,new gas new plugs.it will run all day from about 2000 rpms and up but stop and idle or shut down it just wont get up and go.im thinking fuel pump or wires,any help or ideas would be great,the boat sank last year (not running)up to the cover gasket on the eng and i think some water got in but we ran it the rest of last year with no problems.does it sound like a power pak going?,oonce again thanks for any help.
1971 18' winner
1969 115 jonny
"THURSDAY"

 

[DJ]

Re: 1969 jonny 115 losing cyl at low idle?

Check EVERY ground wire you can find-especially the block to battery ground.

Also look at the #4 plug wire, that is the one lowest on the right side (standing behind). Is it touching anything?

Also, I have no idea what has been done to that engine. If you don't know when the carbs were rebuilt, it's time.

 

[tashasdaddy]

Re: 1969 jonny 115 losing cyl at low idle?

get an induction timing light (buy or borrow) connect it to the battery properly, then when missing connect it to each plug wire keeping track of the results. what you are looking for is an inconcistent flash of the light. this will tell you which cylinder you are loosing. or it could be dirty carbs, it's definately to for a decarb with a product like Seafoam Deep Creep. find in the engine faq forum. removes the old built up carbon from the guts. had a 69 115 johnny as a teenager. run the hell out of it. but went thru power packs every 2 years.

 

[captainspike]

Re: 1969 jonny 115 losing cyl at low idle?

thanks guys,eng was rebuilt 4 years ago but i havent rebuilt the carbs yet,doing a decarb tonite or tomorrow,the # 4 plug was a lttle nasty looking as was the boot so im replacing all of those,will look into a carb rebuild,is that hard to do have the good manuel but was wondering about any tricks you might know.i thought the powerpak theary of it heating up then shuting down was a sign its dying,the eng acts up only at low idle or when you shut down for a couple of minutes.l love boating hahaha thanks for all your help,,can i just clean the carbs or is it better to just rebuild?thanks again guys
1971 18' winner
1969 115 jonny
"THURSDAY"

 

[tashasdaddy]

Re: 1969 jonny 115 losing cyl at low idle?

imho. you are wasting your time just cleaning and reassembling, too many chances off doing it again, use the rebuild kit with new floats, the old ones get to where the don't float properly.

 

[captainspike]

Re: 1969 jonny 115 losing cyl at low idle?

thanks tashasdaddy sounds like good advice will follow,i appreciate alls help,off to lake umbagog this weekend for some smally fishing and dont want any problems,,,,is it hard to rebuild these?have a good manuel so im not to scared..hahahahaha.......thanks once again everyone!!!
1971 18' winner
1969 115 jonny
"THURSDAY"