Johnson '73 85hp Will not idle properly

martys

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• Oct 12, 2003

• #1

Untill last weekend, the motor ran fine (for all these years). Now, the motor is hard to start (warm or cold) but eventually it will. Once it starts, I constantly adjust the idle arm to keep it from stalling. If I put it in gear and go fast, the motor runs fine. When I slow down and try to go under 5 knots, it will bog down and stall. I checked the battery, gas tank, gas flow, and spark plugs, found no problems.<br /><br />Could it be carburetor or other electrical problems?<br /><br />Thanks for some help.

 

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ezeke

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• Oct 12, 2003

• #2

Re: Johnson '73 85hp Will not idle properly

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Last edited: Oct 5, 2007

V

vegard

Petty Officer 2nd Class

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• Oct 13, 2003

• #3

Re: Johnson '73 85hp Will not idle properly

I definitely agree with the above post. I have a 74' 85hp, and it had some problems, and I skipped some of those steps... it came back to bite me in the *** . it sounds like its a carb cleaning problem though.

 

martys

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• Oct 14, 2003

• #4

Re: Johnson '73 85hp Will not idle properly

ezeke & Vegard<br /><br />I tried your suggestions, doubled checked all your ideas. I had the same result when I raise the gas tank even with the fuel pump and applied slight pressure to the bulb.<br /><br />If the next step are the carbs, should I try to clean and rebuild them or have it done professionally?<br /><br />Thanks, <br />Marty

 

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ezeke

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• Oct 14, 2003

• #5

Re: Johnson '73 85hp Will not idle properly

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Last edited: Oct 5, 2007

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medic2051

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• Oct 14, 2003

• #6

Re: Johnson '73 85hp Will not idle properly

Get a OEM manual and rebuild yourself. Take your time, it's not difficult.

 

martys

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• Oct 16, 2003

• #7

Re: Johnson '73 85hp Will not idle properly

ezeke,<br />Since it is at the end of the year and the boat will be in my back yard for about another 2 wks., <br />I would like to try your steps for about an hour.<br /><br />Thanks,<br /><br />Marty

 

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Solittle

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• Oct 16, 2003

• #8

Re: Johnson '73 85hp Will not idle properly

Homework:<br /><br /> http://www.outboardrepairs.com/carburetors/

 

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ezeke

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• Oct 17, 2003

• #9

Re: Johnson '73 85hp Will not idle properly

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Last edited: Oct 5, 2007

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ezeke

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• Oct 18, 2003

• #10

Re: Johnson '73 85hp Will not idle properly

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Last edited: Oct 5, 2007

F

Forkin' Crazy

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• Oct 18, 2003

• #11

Re: Johnson '73 85hp Will not idle properly

I would rebuild them or have them rebuilt. The condition you are describing is a lean condition. To verify this you can use the choke intermittantly and the engine should speed up instead on dieing.<br /><br />Use an OMC jet driver pn 317002. They are not expensive and will not damage the jet like a common screw driver will. You will also need a float level gauge also available at your OMC dealer. This will give a reference to the proper float level which controls the fuel level in the fuel bowl. You may need to replace the needles and seats, and fuel bowl gaskets too. You can use the carb base gaskets if you don't tear them up when you take the carbs off.<br /><br />Use carb cleaner or OMC's engine tune. I like the engine tune b/c it is not so hard on the skin. Compressed air is also a great tool. With a rubber ended blower so you can blow out any crud that maybe blocking passage ways in the carb body.<br /><br />The best advice would be to get a manual, although no longer avaliable from OMC, there are other publishers that make them.<br /><br />BTW I would not use metal wire to clean the jets. The jets are made of brass and the wire may damage the orface which is very critcal to a good running engine.<br /><br />Good Luck!<br /><br />FC

 

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ezeke

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• Oct 18, 2003

• #12

Re: Johnson '73 85hp Will not idle properly

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Last edited: Oct 5, 2007

F

Forkin' Crazy

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• Oct 18, 2003

• #13

Re: Johnson '73 85hp Will not idle properly

Apparently not for my cloudy little mind...LOL!<br /><br />You may use what you want, but if I were to stick anything into a jet, it would be a soft plastic. If probing metal into the jet scratches the orface of the jet, it could change the flow characteristics. The best way is to disassemble and clean.<br /><br />FC

 

F

Forkin' Crazy

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• Oct 18, 2003

• #14

Re: Johnson '73 85hp Will not idle properly

BTW, if the older carbs operate like the newer (6-8) years, the idle is not controled by a jet. It utilizes an emultion tube which mixes air and fuel into an air/fuel emulsion. It then has an air bleed orifice(on the later carbs they are located in each of the carb throats, upper towards the center) which mixes a metered amount of air with the fuel-air emulsion. If it is lean, you have to take it apart to unstop the emulsion tube. The best way to clean them is to have a vat of carb cleaner (I like Berrymans) and let it soak over night. Wash out with water and blow it out with compressed air. They do make, or did, the cleaner in a gallon can instead of a 5 like I have. Note: DO NOT put plastic parts in the cleaner. They likely will not make the trip. <br /><br />FC

 

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ezeke

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• Oct 18, 2003

• #15

Re: Johnson '73 85hp Will not idle properly

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Forkin' Crazy

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• Oct 18, 2003

• #16

Re: Johnson '73 85hp Will not idle properly

ezeke, I see no problem. Thanks anyway! My skin is pretty tough. And I did not mean to sound condescending. <br /><br />FC

 

martys

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• Oct 22, 2003

• #17

Re: Johnson '73 85hp Will not idle properly

Ezeke, <br /><br />I tried your suggestion with spraying the carbs and had some limited success. Now, the motor will idle fine to about one-third up on the idle arm. The motor will still stall at idle speed.<br /><br />After I was finished running the motor, I checked the spark plugs and found them throughly soaked in fuel. After cleaning them I checked for spark, every one had a good blue arc.<br /><br />I am going to try one more time cleaning the carbs and make sure I have clean spark plugs.<br /><br />I'll tell you the results.<br /><br />Marty

 

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ezeke

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• Oct 22, 2003

• #18

Re: Johnson '73 85hp Will not idle properly

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Last edited: Oct 5, 2007

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vegard

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• Oct 23, 2003

• #19

Re: Johnson '73 85hp Will not idle properly

Rebuilding the carbs on that old motor is easy, dont let us scare you. Ive done it a few times, on the exact same engine. just get the kits and follow the directions in the manual. I also recommend that you dont remove the jets. Just pull the core plugs and use lots of carb spray to get all the junk out of them.

 

martys

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• Aug 26, 2007

• #20

Re: Johnson '73 85hp Will not idle properly

I bought the rebuild kits and had them professionally done. Material and labor, it was only $125. Bolted the carb back on, and fired up. The engine runs fine now.

Thanks everybody for your help, this site is great.