1973 20 HP Johnson Outboard

[John Newcomb]

Hey Guys, Hopefully someone can help me with this. I just bought a boat and motor and it had sat up for 2 years. I found trash in the fuel pump and carburetor and cleaned it thoroughly. I also replaced the spark plugs and gapped them to .030. I replaced the fuel lines within the coweling. Now it cranks right up and runs for about 15 minutes and then becomes sluggish and starts to die out. It eventually quits and oh yea, I have to leave the choke open about halfway for it to run.... I am new to this so any advice would help..

 

[BF]

Re: 1973 20 HP Johnson Outboard

Does the spark look good on both plugs? Does it still look good after you've warmed up the engine and it dies? My guess would be a bad coil(s) that shows up when it warms up. Maybe you need choke because you're only running on one cylinder? Have you checked the compression?<br /><br />Is it pumping water OK? Maybe it's overheating.<br /><br />Those are my thoughts anyway...<br /><br />Brent

 

[JB]

Re: 1973 20 HP Johnson Outboard

Could be overheating, John. If you haven't changed the water pump impeller, do so now. They are only good for a couple of years, including time that they are in storage.<br /><br />If you need choke to keep it running after warm up you might have missed some gumming in the carb orifices.<br /><br />Let us know what you find.