75 Johnson 9.9 missing at idle ?

barnabus

Banned
Joined
Dec 9, 2005
Messages
5
I just took my seahorse to a marine mechanic for a miss at idle. Once powered up it runs fine.They did not do a rebuild because they told me it could be 2 different things.<br /><br />The first of course was that it needed a carb rebuild.<br /><br />The second was that they mentioned a air leak or something at the lower unit which would cause it to suck air? <br /><br />Ive already given them $85 for basically just changing out plugs as it not idling any better now than before. They say a carb job would be another $125.00 but thet cant guarantee its the carb but could be the air problem.<br /><br />How can I tell if its the air/exhaust problem? Do any of you know what the mechanic is talking about and how I can check that myself to detemine if it only needs the carb job.Please help!
 

barnabus

Banned
Joined
Dec 9, 2005
Messages
5
Re: 75 Johnson 9.9 missing at idle ?

Come on Guys,how about some help.Duck season is upon me.Thanks!
 

rolmops

Vice Admiral
Joined
Feb 24, 2002
Messages
5,519
Re: 75 Johnson 9.9 missing at idle ?

Throw a can of carburetor cleaner into your fuel tank and take it for a nice long ride.After about half an hour,try and adjust the needle valve to that sweet spot.There is a good chance that this will solve your problems.
 

MCM

Lieutenant Junior Grade
Joined
Jun 1, 2005
Messages
1,201
Re: 75 Johnson 9.9 missing at idle ?

Just backing up rolmops suggestion, try some Seafoam, 2+4, etc. in the tank, probably some blockage in the jets/passages. I think an air leak would tend to affect it throughout the rpm range more so than just at idle.<br /><br />Good Luck :)
 

yater

Petty Officer 3rd Class
Joined
Jun 12, 2005
Messages
79
Re: 75 Johnson 9.9 missing at idle ?

Pull the carb apart and clean it...no big deal. You'll lose your a$$ at the dealer if you can't do the simple maintenance.
 
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