Johnson 9.9 wont idle

Valcuba

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Feb 4, 2002
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4
Help! My Johnson 9.9 starts pretty wel but will not idle. Conks out after a couple of seconds. If i throttle up to full it will stay on but once i drop down it turns off. Any ideas?
 

petryshyn

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Oct 3, 2001
Messages
2,851
Re: Johnson 9.9 wont idle

Hi<br />Has it run well recently for you? Have you adjusted the idle mixture screw?<br />Sounds like a idle circuit problem. How long has it been sitting? How old is fuel? Has it been apart for any reason that would affect timing? You can try the easy way to purge the idle circuit, providing it hasn't sat dorment for too long a time. Start it up, rev up to a safe high RPM, quickly jam a rag over the carb opening to completely choke it off, allowing engine to die. Restart engine (will be flooded, so do not choke) Sometimes this will clear a small blockage. If it didn't help, back out idle mixture screw 2 turns, and choke with a rag again. Now if it doesn't help....remove and clean carb.<br />I've also had luck with removing idle mixture screw and spraying carb cleaner into screw bore, then forcing it in further with compressed air. Reinstall screw, and retry.<br /><br />Good luck... :)
 

Valcuba

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Feb 4, 2002
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4
Re: Johnson 9.9 wont idle

As a matter of fact yes, it had sat for a couple of weeks, but the fuel is fresh. it hasnt been taken apart. Last time i ran it it worked perfectly. Im thinking the timing may be off. How do i check that?
 

petryshyn

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Oct 3, 2001
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Re: Johnson 9.9 wont idle

How can the timing be off if it ran good the last time?
 
D

DJ

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Re: Johnson 9.9 wont idle

Ditto Schematic. DO NOT SPRAY CARB CLEANER DOWN THE THROAT WITH THE ENGINE RUNNING. It's OK as Schematic describes it.<br /><br />It's definetely fuel related in the idle circuit.
 

Valcuba

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Feb 4, 2002
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Re: Johnson 9.9 wont idle

Thanx shematic. Ill give your fix a try as soon as the soreness in my arm from all that cranking the other day wears off. In order to rev up to a high rpm tho, i have to pop it in gear. Is that a concern?
 

petryshyn

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Oct 3, 2001
Messages
2,851
Re: Johnson 9.9 wont idle

Will it not stay running at highest throttle attained in neutral? If not, I'd rather not see you run it out of water in gear.<br />>the prop would love to bite you<br />>the engine is very easy to over-rev out of water, and the rods will want to leave the engine and hurt you....<br />>if you can get it to run in neutral, thats fast enough<br /><br />If you can't get it to run in neutral, do the safest fix first, it may solve your problem without the danger of running in gear.<br />>remove idle screw, spray carb cleaner into screw bore, force it further in with shop air (safety glasses on please) reinstall screw till just bottoms with finger tips, back out 1 1/2 turns......retest. If that doesn't cure it, pull the carb and clean properly.....<br /><br />good luck!<br /><br />Play Safe!! ;)
 

Valcuba

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Feb 4, 2002
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4
Re: Johnson 9.9 wont idle

Thanx alot schematic. I checked my original post and realized i had not mentioned the fact that it wouldnt rev in neutral. Im going to try your fix this weekend and hopefully have fish for dinner on Sunday. I appreciate your help.
 
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