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1980 Johnson 15 idle question/help please!

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williej

New member
My son purchased this 80' johnson 15hp motor (J15RCSD) for 40 bucks. It didn't run when he got it. I checked compression, it is 70 on both. Replaced worn pinion starter gear. I had to replace the broken cam follower, set it where the roller touches the mark on the cam plate and starts to open the throttle plate. put new fuel pump on it. new plugs. it has good spark, will jump 7/16 with a good pop. cleaned carb the first time and then got a kit and rebuilt it completely the second time. I adjusted the idle needle screw backed it off 1.5 turns, then adjusted it in by 1/8 increments till it started coughing then back out 1/4 turn. Now it will start with the throttle opened mid to wot. seems to run pretty good now. My question/problem is that it will not stay running at idle unless the cam roller is touching the mark on the cam plate, if the throttle is decreased any lower it dies. In advance, thanks for all time and effort in assisting me!!
 
I am not an expert! I did have an idle problem with a different engine and the cause was an air leak in the fuel delivery. The fuel pump could not overcome the leak at low rpm and the carbs would starve for fuel. I replaced all hoses and primer bulb making doubly sure that the fittings were well secured and this cured the problem. I found this out by placing a fuel tank above the fuel pump and running the engine while gravity feeding the fuel. This may not be your problem, but it is worth a quick trial to see.

Good luck,

Richard
 
well guys...... i think i solved the problem i was having, just a little tweaking to the carb did it. THANKS for all the help!!!!!!!!! as i was working on it i noticed that water was beading up around the head gasket. i pulled the head and found blown gasket a little bit of water residue in the bottom cylinder. no damage to cylinder walls no corrosion everything appears to be ok. is it anything else i should do or check before getting a new gasket and putting the head back on???
 
Hard to day without seeing the motor and knowing details from previous owner.--------If water got " inside " the crankcase and sat there for any length of time you could have major rust problems internally.------Just run it and time will tell.
 
thanks!! i believe it just happened according to the looks of the cylinder walls. they look pretty clean. i was told this motor has been sitting up for about three years and was running fine before. thats what he told my son anyway.
 
i have torn into a few motors before. but this is my first outboard. this is a great forum!!! i have learned alot just by reading at first and then the help from all the replies!!
 
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