68 johnson sputters

[dan-n-kim]

you guys helped me last time so i'm back for more. i have a 1968 20hp johnson. I changed the prop from a 9x10 to a 9x9, rebuilt the carb and a new thermostat. Boat ran great for a while then not so much. WOT with just me was 5000 rpm. With two of us its 4700. Once i get opened up i'm good. But be for that it's almost like it's loading up: it sputters and smokes and chokes. I read the manual but there is nothing in the trouble guide that fits me. Any ideas where i might go? I even rebuilt carb again thinking i lost a gasket or something and still nothing. HELP!

 

[Daviet]

Re: 68 johnson sputters

Good compression and spark?

 

[dan-n-kim]

Re: 68 johnson sputters

compression is 125 and great spark. new plugs too. i thought i may have over reved it but it still runs good wide open.

 

[Daviet]

Re: 68 johnson sputters

Check ad see if the mag plate is advancing all the way.
With good compression and spark, the only thing left is fuel delivery.
Try squeezing the primer bulb and see if it helps.

 

[dan-n-kim]

Re: 68 johnson sputters

I'll recheck compression,vac lines, and fuel lines tomorrow. I'll post results.

 

[dan-n-kim]

Re: 68 johnson sputters

ok checked the compression again: top cyl is 120, bottom cyl is 115 and has a wet plug. Looks like oil. Gas line full and primer is hard all the time. Vac lines look good as well. Everything moving back and forth full motion. Could this have anything to do with the points and condensors?

 

[dan-n-kim]

Re: 68 johnson sputters

wondering if the points are breaking down?

 

[dan-n-kim]

Re: 68 johnson sputters

ok. i put a spark tool on plugwires and can only get it to jump a 1/4 inch. the bottom wire (the one thats wet) is sparking intermitantly.???????????

 

[oldcatamount]

Re: 68 johnson sputters

kinda sounds like a bad coil or, a bad plug wire to that cylinder.

 

[dan-n-kim]

Re: 68 johnson sputters

me too. trying as we speak to get fylwheel off. errrrrrrrr!!!

 

[dan-n-kim]

Re: 68 johnson sputters

i cant get the flywheel to budge! puller tight and i dont wont to break it. any ideas?

 

[oldcatamount]

Re: 68 johnson sputters

try a sharp rap on the top of the puller while it has tension on it with a mallet (not a hammer!)

 

[dan-n-kim]

Re: 68 johnson sputters

ill have to use a piece of wood with a hammer. dont have a mallet. let me try.

 

[dan-n-kim]

Re: 68 johnson sputters

wow!! got the flywheel off. flywheel rubber one of the coils. points look ok just a lil out of adjustment. one .019 and the other.021.

 

[oldcatamount]

Re: 68 johnson sputters

did you mean "flywheel is rubbing one of the coils"? if so, that is not good. could be a short right there.

 

[dan-n-kim]

Re: 68 johnson sputters

thats what i thought too but there is no wire showing. what bothers me is why did it rub? all screws r tight. could the crank have dropped a bit? i did notice while i was pulling the flywheel there was up and down play.

 

[oldcatamount]

Re: 68 johnson sputters

the "up and down" play should be very slight. I suppose it's possible that some has put in a coil that's a little to big for that motor but I really doubt that. Make sure that the coils are flush with the "boss" and not sticking out at all. Since you have the flywheel off, maybe you should consider some new points and condensers while you're in there. Points can look good but not work correctly. Keep in mind that I'm only guessing here.

 

[dan-n-kim]

Re: 68 johnson sputters

put it all back together. no spark at all on bottom cyl. gonna get coils, points and cond.

 

[dan-n-kim]

Re: 68 johnson sputters

OK. got new coils and points, installed, one new coil went out instantlly! put old good one back in. 1000 ohms lest then new one but running. gonna check carb this weekend. still have slow sputtering pick up. maybe i missed something.

calling parts right now for new coil!

 

[dan-n-kim]

Re: 68 johnson sputters

ok something new..... full in a vacuum line. any ideas on this one?????