# Outboard Stalling at low idle........??????



## gotwipers (Mar 31, 2007)

I have a 1990 40HP Johnson outboard (same boat I was gonna sell, thank goodness I didn't!), new floats and carbs cleaned I am having the same issue. Wide open the motor runs smooth as can be, as soon as I pull back on throttle the motor falls on its face. If I unhook the fuel line the motor smooths out and runs up and down the rpm range until it runs out of fuel. Is this a low idle adjustment or needle problem? I cracked the gas cap thinking it may be a vaccum issue but no change was noticed. Once the motor is warm and is off for a while it will start right up but floods out almost instantly....I will try and answer questions the best I can if there are any.

Thanks in advance!


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## Hetfieldinn (May 17, 2004)

How old is your primer bulb on the fuel line?


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## freyedknot (Apr 10, 2004)

you could try and adjust your idle speed up a bit, maybe that would help? how slow does it push your rig now? my 40 on a 16.5 ft aluminum only goes to 1.5 mph on a good day with a calm head wind.


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## gotwipers (Mar 31, 2007)

Hetfieldinn said:


> How old is your primer bulb on the fuel line?


replaced from tank to motor with brand new.


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## gotwipers (Mar 31, 2007)

freyedknot said:


> you could try and adjust your idle speed up a bit, maybe that would help? how slow does it push your rig now? my 40 on a 16.5 ft aluminum only goes to 1.5 mph on a good day with a calm head wind.


I was wandering if with the carb work done that I would have to adjust it. I am not sure how slow I can idle but it is probably close to that. Right now I cannot run slow speed at all unless I disconnect the fuel line


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## freyedknot (Apr 10, 2004)

then it sounds like you have a small air leak somewhere in the connections.


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## gotwipers (Mar 31, 2007)

ok, it is a head scratcher for sure. What about hooking up an external tank, just to eliminate the chance my breather or on board tank is bad?? I did loosen the filler cap (while running) and checked the breather before I took it out again.


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## Ðe§perado™ (Apr 15, 2004)

It is your low idle adjustment. Screw it all the way in and unscrew it about a turn and a half and run the motor and start from there. I had the same problem and if the adjustment doesn't work try taking the carb apart and remove the idle needle and blow carb clener in it. I ound dirt down in mine and it fixed it. Hope this helps.


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## cincinnati (May 24, 2004)

Check for sticking float needle. Motor is able to keep pace w/excess fuel delivery @ higher RPM but floods @ idle.


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## peple of the perch (Sep 13, 2004)

Does the motor "cough" if so than it is running too lean. Are you choking it when the motor floods out?


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## M.Magis (Apr 5, 2004)

Who cleaned the carbs and how was it done?


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## nikmark (May 26, 2009)

I'm with Cinci, sounds like the carb float is sticking and not shutting off the flow of gas. Result is the engine is flooding with gas and stalling. That's why disconnecting the fuel line is temporarily fixing the issue, your manually stopping the flow of gas.


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## firstflight111 (May 22, 2008)

check you gas line for holes


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## gotwipers (Mar 31, 2007)

peple of the perch said:


> Does the motor "cough" if so than it is running too lean. Are you choking it when the motor floods out?


don't know if I would consider it a "cough" lol, but when I do back off of the throttle it hiccups then stalls. No I am not physically hitting the choke, only when I try and restart the engine....


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## gotwipers (Mar 31, 2007)

firstflight111 said:


> check you gas line for holes


Brand new line, but will check that also.


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## gotwipers (Mar 31, 2007)

M.Magis said:


> Who cleaned the carbs and how was it done?


A friend of mine and myself, he is a mechanic and I trust him to do the work. As far as how it was done, we un-bolted the linkage, removed the fuel lines and took the carbs off. We didn't move any of the linkage, took the carbs in the garage and placed them on the bench. removed the bowl, cleaned them using some nasty carb cleaner, blew air threw the needles, replaced floats, checked floats, etc, put new gaskets on and then moved on to the next one....lol, that's a short version of it. I am not sure what you are looking for as far as how was it done but I gave it a shot!


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## gotwipers (Mar 31, 2007)

Thanks for the input guys, I haven't had time to look at the motor yet, this is my long week of work so I may not get to it for a couple days yet. 

With the input I have gotten from you all and from what others are saying it is a good bet I will start with the floats first.


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## gotwipers (Mar 31, 2007)

This is the update, took to a local shop and had them look at it since I was getting nowhere. They found that the motor was only running on one cylinder and that the pilot jet was plugged off. 

Before the engine would run full throttle at 4200 rpm, after the fix it is around 6000 rpm, and smooth as can be. No more stalling at idle or flooding out. Did a compression test, charging system test, and gave me tons if advice in adjusting the carbs if I need to. Great experience dealing with them and will be going back.




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## MassillonBuckeye (May 3, 2010)

gotwipers said:


> This is the update, took to a local shop and had them look at it since I was getting nowhere. They found that the motor was only running on one cylinder and that the pilot jet was plugged off.
> 
> Before the engine would run full throttle at 4200 rpm, after the fix it is around 6000 rpm, and smooth as can be. No more stalling at idle or flooding out. Did a compression test, charging system test, and gave me tons if advice in adjusting the carbs if I need to. Great experience dealing with them and will be going back.
> 
> ...


Whos the Shop? I'd say they deserve a kudos for helping you out! All too often people only pass their complaints along.


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## AC_ESS (Nov 15, 2008)

do what every manual says.. start with the gas can then work you way to the carbs. If you have done that I would check you idle adjustment


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## gotwipers (Mar 31, 2007)

Mark Beavers, Beavers Marine in Mineral City.

AC ESS, I was just updating the thread. The issue is fixed thanks to a mechanic....


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## captk (Mar 13, 2008)

Did the tech tell you what was the issue? im thinkin snyc and link.


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## fishnguy (Apr 14, 2004)

I had the same issue last year and they replace my cyclinder. Can anyone show with a picture what the idle adjuster looks like. 

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## gotwipers (Mar 31, 2007)

There is only one adjuster on the Johnson I have, tri-plex carb system. I will describe the adjuster and post a pic tomorrow. It is on the carb and has a brass collar or sleeve, this is your low adjustment screw and should be adjusted 1/4 turn at a time.

Mark the start position, turn no more than 1/4 turn and wait for 15 to 20 seconds for adjustment to settle in. Keep adjusting until the engine settles in. My carbs are adjusted with the top being 6 full turns out to the botom only 3 full turns out. Tech suggested this is normal for tri plex carbs....



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## gotwipers (Mar 31, 2007)

captk said:


> Did the tech tell you what was the issue? im thinkin snyc and link.


Without getting to technical he did. They couldn't get the motor to idle at all, they checked everything that was obvious and still had the same issue, they then took a dropper of fuel and dumped it onthe bottom cylinder, the motor took off and idled for a couple seconds, they found the issue was with fuel delivery to that cylinder. He said the pilot jet was clogged up, they cleaned it out (and from what I understand) the carbs synced back up and the rest was just adjusting it in a barrel. Again that's the short version.... He said that the motor had good spark, coils checked out good so they started looking a little deeper. 


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