1973 Johnson seaking 20 hp

Just bought the motor yesterday. Threw it in a trash can and pulled it over. Would run for about 3-5 seconds then pop (backfire) and die. I sprayed some carb cleaner in it and it would stay running longer. The more I sprayed it before pulling it over the longer it would run. Anyways I broke the recoil spring and just went to pick one up. The older guy at the marina said i probably broke it because my flywheel key is sheared? He said its throwing the timing off and causing it to backfire. My first instinct was that my carb is gummed up. The motor hasnt ran in 4 years. Is my flywheel key possibly sheared, or do you think its a gummed up carb? Any input would be VERY much appreciated.



Thanks, Andrew

Re: 1973 Johnson seaking 20 hp

Usually a sheared key won't run.See if a little choke helps it run.
Its very likely the fuel system needs attention after all that time.
And if you try to run it too much without a carb rebuild and system check
the carb will just keep getting fouled.

Re: 1973 Johnson seaking 20 hp

Alright thanks. I tried running it with just a little choke. Didnt seem to make a difference. Im gunna go out and tear apart the carb and clean it up a bit. Also, when I put that recoil spring in do I need to grease it before I put it in?

Re: 1973 Johnson seaking 20 hp

Hi chief. A carb rebuild should help clear things up quite a bit. You don't really need any grease on the recoil spring. A light coating of WD-40 will be fine. I have a '66 20 hp that I just brought back to life. I love it, and it was pretty simple all and all, and now she runs like a top. Holler if you get stuck. Here are some handy links.

http://forums.iboats.com/showthread.php?t=158086
http://www.duckworksmagazine.com/07/columns/max/index1.htm
http://forums.iboats.com/showthread.php?t=167352

Re: 1973 Johnson seaking 20 hp

And DO NOT run your motor on carb cleaner! It'll clean the innards of any oil and you can seize up your motor!

Re: 1973 Johnson seaking 20 hp

Well I sprayed a descent amount in it yesterday when I was attempting to start it. Id say I probably went through 1/4 can maybe a little less... Anyways I took the carb off and it was gummed up bad. Cleaned it up really good, sprayed all the jets and got them cleaned. So did I ruin my motor or what?

Re: 1973 Johnson seaking 20 hp

Nah you probably didn't ruin it, but don't use any more going forward. Carb cleaner is designed to break down and remove oils, which is fine for cleaning the carb while it is removed from the motor, but you don't want to use it while the motor is running as it will dissolve/remove the oil which is needed to lubricate the innards of the motor. You should be ok, but just make sure you use proper fuel oil mix going forward. I would use 24:1, which is about 5.5 oz of TCW-3 oil to 1 gal of 87 octane gas. You can keep a small spray bottle of them same fuel/oil mix to spray into the carb should you ever need it.

Re: 1973 Johnson seaking 20 hp

Alright that makes me feel better...I just got my first outboard 2 years ago. I am only 21, but am a big time fisherman. So I know I need to learn my way around the motors. Now I am guessing that my fuel filter is probably nasty as well, and I am curious if there is any way I can clean the diaphragm without ripping it. I know it makes more since to buy a new one but I am in a pinch and want to get out fishing tomorrow morning.

Re: 1973 Johnson seaking 20 hp

Skip the 24:1 mix and use 50:1 which was recommended in 1973....

Re: 1973 Johnson seaking 20 hp

Yup I did. Thats what I was running it on was 50:1. Thanks everybody. This site is awesome

Re: 1973 Johnson seaking 20 hp

Hi chief. The 50:1 should be ok. I suggested 24:1 to be on the safe side. Better a bit too much oil than not enough. Any way, as for cleaning the fuel pump. There's not a lot you can do. You may be able to remove/loosen the black plastic tab/disc so you can get a look at the fuel pump screen and clean it if need be, but that's about it. Unfortunately, a lot of the fuel pumps don't have rebuild kits, so you have to buy a whole new pump, get one off of a donor motor, or use another aftermarket, small engine fuel pump made by companies like Briggs and Stratton. That being said, fuel pumps usually don't go bad for no reason. Do you have any reason to think it is bad? If so, there are a few tests you can do to confirm if the pump is working or not. You can disconnect the fuel line from the fuel pump to the carb (at the carb end) while the motor is running to see if fuel is being pumped out of the fuel line. You can also test it by pumping up the primer bulb with the motor shut off. If it gets and stays hard, then the fuel pump is probably ok. If the motor runs poorly unless you manually pump fuel to it with the primer bulb, then the pump is probably bad. Give these a try before you give up on the pump. New OMC replacement pumps are about $55 + :/ Keep us posted.

Re: 1973 Johnson seaking 20 hp

well this morning I cleaned that wire screen. So the car is cleaned and the pump looks good. I tried starting it up and on the second pull it sounded like it wanted to go. After that nothing....I think I may have flooded it. So I pulled the plugs out and am have been letting it sit all day/night. Any ideas???

Re: 1973 Johnson seaking 20 hp

Gunna check for a good spark in a little bit. I dont know what else it could be

Re: 1973 Johnson seaking 20 hp

Alright. Im stumped now. I have spark in both cylinder. I have a clean carb, and I have good compression....I even put some of my 50:1 mix I run through the motor in a spray bottle and sprayed the carb. So even if my fuel pump wasnt working it should still fire I would think.. Still nothing....It is weird. It sounds like it will on the first or second pull of the day and after that nothing...

Re: 1973 Johnson seaking 20 hp

Anybody have any insight? Could this be a timing issue?

Re: 1973 Johnson seaking 20 hp

If the flywheel key is intact and the points are gapped correctly, then it probably isn't a timing issue. Spark, fuel and compression. If you have those three items, timed correctly, the motor should run. I'd go back through and make sure everything is good to go. You say you have good compression - what are you readings? How do your plugs look? Wet, dry? What plugs are you running?

Re: 1973 Johnson seaking 20 hp

When I bought it the other day the guy took readings and it was 110 in top 108 in bottom. The plugs are wet but not soaked. I am running champion j4c's I believe

Re: 1973 Johnson seaking 20 hp

Alright well I just ran through and check spark again. apparently my brother cant see because I am only getting spark in the top cylinder. where should I start from here?

Re: 1973 Johnson seaking 20 hp

Hi chief. There are a few things you can try. For starters, I would suggest getting a proper s'plug gap tester from the auto parts store for a couple bucks. That way you can properly gauge the strength of your spark. You should ultimately get a bright, blue spark that jumps a 1/4" gap. The old "ground the plugs on the engine block" trick isn't very accurate (even though we've all done it). While there are a couple tricks to try and get the spark back, I would suggest you just rebuild the magneto. It's cheap, quick and easy and you'll have a virtually new igniton system that will be trouble free for years to come. Assuming your coils are OK, you can get a tune up kit (points and condensers) for about ($20), new 7mm copper core spark plug wires and boots for about $3 a foot (10 ft. is plenty, $30), and a couple new Champion J6C plugs ($10). There are tons of threads that can walk you through the job and I'll include a link that will help too.
That being said, you can try a few tricks that may get some spark back. One is to try to swap the plugs just to make sure it's not as simple as that. If that doesn't work you can try trimming off about 1/2" of the old s'plug wire and reattaching the boot in an attempt to remove some corroded wire.
You can also try cleaning and regapping the points to .020". Make sure they're very clean and properly gapped. You should also take a look at the coils to see if they're damaged in any way. Give these a try and report back.


http://www.duckworksmagazine.com/07/columns/max/index1.htm

Re: 1973 Johnson seaking 20 hp

Thanks for the great information. I did just get in and I tested the spark 1 last time. This time in a dark room. I am in fact getting spark in the bottom cylinder but only about once or twice out of 10 times while the top is getting spark 10 out of 10 times. could this be something as simple as a bad plug wire boot or something?