Problem with 120hp Johnson

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Terry H

Lieutenant Commander
Joined
Sep 25, 2001
Messages
1,862
I have a problem with a motor that has me in a quandry...I started it up this morn on a hose and it started right up as it always has. Been 2 months since I last ran it. The problem is that it is idling at 1800-2200 rpms on the tack...way too fast. It will run for a second (at 2200)then miss (down to 1800) then back up. Starboard plugs are oily and clean. Other 2 are sooty with oil...normal. Using timing light found no fault with spark. I mix gas/oil in fuel tank...2 mos old, using OMC oil. I've never had a problem with this motor before and this has me stumped...tiv for whatever you can do to help.
 
B

BKool68

Petty Officer 1st Class
Joined
Oct 14, 2001
Messages
259
Re: Problem with 120hp Johnson

A motor on muffs and a motor in the water can behave really different. Try some new plugs and a run in the water to see what she really is up to. If you have a spae fuel tank try some fresh fuel too.
 
T

Terry H

Lieutenant Commander
Joined
Sep 25, 2001
Messages
1,862
Re: Problem with 120hp Johnson

Btw...it's a 1990 year and has a jet pump on it...bkool, i have run it on hose many times and it normally idles smoothly at 1000 rpms. There won't be any lakes open here for a while yet and I don't want to take it on the "River of no return" without reliable power. Thanks for the Thought
 
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DJ

Guest
Re: Problem with 120hp Johnson

Thought 101,<br /><br />Are your control cables binding. Unhook the throttle control cable and see what that does. You should be able then to push the throttle linkage all the way back.<br /><br />The only other thing I can think of is that it is running lean. Take a close look at your fuel line connection and hoses under the cowl.
 
T

Terry H

Lieutenant Commander
Joined
Sep 25, 2001
Messages
1,862
Re: Problem with 120hp Johnson

djohns...a couple of the plugs would lead me to believe it could be too lean...would that make it idle so high? I'll replace the filter and see if that helps...thanks
 
T

Terry H

Lieutenant Commander
Joined
Sep 25, 2001
Messages
1,862
Re: Problem with 120hp Johnson

I checked the filter, it's fine. Control cables are also fine, but I did find a fuel leak coming from the oil inlet line that I capped off. I'll redo the cap but would that cause the idle to be so erratic? thanks for the thought
 
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