1971 Johnson 25hp (No Spark in Top Cylinder)

[Daviet]

Re: 1971 Johnson 25hp (No Spark in Top Cylinder)

Can't get the vids to play. Could it be a lean sneeze? Try opening the low speed jet about a 1/4 turn and see if it helps.

 

[Monte1961]

Re: 1971 Johnson 25hp (No Spark in Top Cylinder)

Open up you low idle jet more. 1/4 turn at a time. Yes Daviet it's a lean sneeze! Other than that, motor sounds good! Have fun!

 

[Sixmark]

Re: 1971 Johnson 25hp (No Spark in Top Cylinder)

I was able to watch the video, is the prop engaging and then disengaging while this is happening?

 

[Daviet]

Re: 1971 Johnson 25hp (No Spark in Top Cylinder)

Geez, what did we do before videos? Yep, lean sneeze.

 

[cajuncook1]

Re: 1971 Johnson 25hp (No Spark in Top Cylinder)

Ok, soooooo thank you everyone for the help, motor is running got to take it out today, and runs awesome wide open, but now if I set and let it idle it runs very weird, idles for about 2 seconds then hear a loud CLUNK then idles again for a few seconds then another CLUNK but nothing when its wide open, see the videos I attached please, they show it very well. Thanks !

[video]http://www.thenerdforce.com/videos/boat1.MOV[/video]
.
[video]http://www.thenerdforce.com/videos/boat2.MOV[/video]

Sounds like you have a lean sneeze. Basically your slow idle needle is not allowing the carburetor to deliver enough fuel at idle, so you will need to richen your delivery.

( Lean Sneeze low speed needle adjustment) Slow the engine down to where it just stays running. Shift into neutral. In segments of 1/8 turns, turn your needle out (counter clockwise). Wait a few seconds(8 to 10 sec) for the engine to respond. As you turn the needle valve out, the engine should stop clunking or lean sneezing and run smoothly.

If you ever have to have the carburetor cleaned and put in a kit, this is Joe Reeves original link and post for adjusting carburetors.

http://forums.iboats.com/showthread.php?t=167352

Good luck!!

 

[Monte1961]

Re: 1971 Johnson 25hp (No Spark in Top Cylinder)

What I don't get is when he said,(SHOW THE PROP< SHOW THE PROP), whats that all about?

 

[cajuncook1]

Re: 1971 Johnson 25hp (No Spark in Top Cylinder)

wow, we all posting about the same time......lol

 

[Monte1961]

Re: 1971 Johnson 25hp (No Spark in Top Cylinder)

Getter done!

 

[Sixmark]

Re: 1971 Johnson 25hp (No Spark in Top Cylinder)

What I don't get is when he said,(SHOW THE PROP< SHOW THE PROP), whats that all about?

Thus my question if the prop was engaging and disengaging, I like to eliminate all other potential problems. I don't put a lot of stock into audio qaulity on videos posted on youtube. So better to ask and be sure than assume.

 

[Vapour1ze]

Re: 1971 Johnson 25hp (No Spark in Top Cylinder)

Thanks everyone for the replies.....

New problem now, just took it back out, to mess with it, didnt even open the lid on the motor and just went up and down river a few times running great then all of a sudden at full power it sounded like the prop just started free spinning and lost all power, engine just revved up like crazy, stopped and proceeded again on my way but if I give it full throttle from a dead stop it starts to sound like it goes then just all of a sudden VROOOOOOOOM free spin, If I hold throttle at like 1/2 way I can put along just fine and plane out ok, but if I go to give it full throttle it like falls out of gear it almost sounds like but it doesnt because if I let off and start going instantly again without nailing it its ok,,,,

it happened earlier today once but was fine because i pulled up the motor and a stick was stuck underneath the motor and the boat and it floated away and then I started it back up and it was fine so I thought that was it, but now its doing it again, and it didn't get better I had to coast all the way home at like 1/2 throttle roughly,,,,,

 

[Sixmark]

Re: 1971 Johnson 25hp (No Spark in Top Cylinder)

Now you know why I asked about the prop earlier, yes it could have been a lean sneeze , but being that you were pointing out the prop at the end made me wonder about a prop slippage or gearbox issue.

Now that you have mentioned the stick, I strongly suggest you check for slippage or even drain the lower unit lube and check for metal shavings.

 

[Vapour1ze]

Re: 1971 Johnson 25hp (No Spark in Top Cylinder)

shifts into all gears just fine still, and the motor in neutral still did the thing where it sounded like it was almost grinding or whatever,,, my buddy just told me he had the same problem before and it was a rubber seal or something in the prop that has to get rehubbed or something like that? or just buy a new prop?

 

[Monte1961]

Re: 1971 Johnson 25hp (No Spark in Top Cylinder)

I think what you are talking about, is a worn out prop hub,If that's what you are talking about? Yup time for a new one or have that one rebuilt! Post back and let us know.

 

[Vapour1ze]

Re: 1971 Johnson 25hp (No Spark in Top Cylinder)

yes , so do i have to buy a new prop? or a new hub or what do I do? how much $$ am i looking at ?

 

[Sixmark]

Re: 1971 Johnson 25hp (No Spark in Top Cylinder)

You can by a new prop or have yours rebuilt, you can look for props right here on Iboats, as they sell them or choose just about any prop shop or marine dealer.

If you lived in Minnesota I could tell you where to go, but I don't know your location

 

[Vapour1ze]

Re: 1971 Johnson 25hp (No Spark in Top Cylinder)

excellent thank you, its just weird because I went out yesterday to try it again and it worked for like 20 minutes then VROOOOOM same problem,,,, so I dont know if the seal holds up for a little bit then gives way after light usage,,,, its weird,,, all my gears go in just fine etc etc, and it doesnt slip out or anything so it must be the prop needs to be rehubbed after the research I've done I'm gonna pull the motor out later today and get the prop off,

 

[cocotower]

Re: 1971 Johnson 25hp (No Spark in Top Cylinder)

Ok onto the next problem, got the flywheel off, got to the points, turned the flywheel until it was at the highest point , which is what I thought was right before the flywheel got easy to turn when the pistons fall back down or whatever, I adjusted the points which were very incorrect and not at .020 I adjusted them to .020 thinking everything is going to work woohooo I'm on my way, because the coils aren't cracked, nope I put everything back together and now I get no spark on eathier cylinder where before the bottom worked and the top didnt, now neither work..... Should I readjust or should I buy the Tune Up kit for 17.99??

Pictures below of coils, which look brand new to me,

I am experiencing the same situation. Setting the points based on the highest part of the shaft for each point gives me no crank at all, where as before the gaps weren't even set and the motor ran.

 

[kfa4303]

Re: 1971 Johnson 25hp (No Spark in Top Cylinder)

HI cocotower. This link may help you get the points sorted out. It's for a different model, but the steps are the same.


http://www.outboard-boat-motor-repa...on 3 HP 1952-1967 Ignition System Tune-up.htm