1976 Johnson 15hp wont run right

[rmd8123]

I have a 15hp motor that i cannot get to run and idle correctly. It will rev up and once in a awhile pop, then at idol it pops a lot more. I tried adjusting the lean/ rich mixture but doesn't seem to help. Anyone have any ideas? Heres a link to a short video of it popping. 1976johnson - YouTube

 

[nwcove]

Re: 1976 Johnson 15hp wont run right

time to clean and re-kit the carb.....dont cut corners on the job. also google leeroys ramblings, lotsa good info there.

 

[rmd8123]

Re: 1976 Johnson 15hp wont run right

I cleaned the carb and put a rebuild kit in it. Is there something i could have put back together wrong or not adjusted or maybe didn't clean good enough?

 

[rmd8123]

Re: 1976 Johnson 15hp wont run right

heres another video johnson15hp - YouTube

 

[Rick.]

Re: 1976 Johnson 15hp wont run right

Sure appears to be a lean sneeze. Try opening you slow speed needle an 1/8 of a turn, wait 20 seconds and do it again. It should stop at some point after adjustment. If not I would suggest re-cleaning the carb. The slow speed needle should be 1 1/2 turns out from gently seated to begin with. Best of luck. Rick.

 

[Willyclay]

Re: 1976 Johnson 15hp wont run right

Maybe this will help: Johnson_carb

 

[dkonrai]

Re: 1976 Johnson 15hp wont run right

did you replace the needle bearing in the carb?
dino

 

[Robj]

Re: 1976 Johnson 15hp wont run right

I would also check the ignition system. Look for cracked coils, check the points, change the condensor. Does the problem go away with the choke on? If it does then it is fuel related, if not then most likely the problem is elsewhere.

 

[dkonrai]

Re: 1976 Johnson 15hp wont run right

I would also check the ignition system. Look for cracked coils, check the points, change the condensor. Does the problem go away with the choke on? If it does then it is fuel related, if not then most likely the problem is elsewhere.

+1 also a compression check too. would not want to fix a motor that had low compression.

dino