1970 Johnson 20hp Carb question

[mhills]

I have some questions. I have a 1970 20hp 20r-70C Johnson for many years. Last year I sank my boat and motor coming out of a river, ya it was not good. Any ways I dried it out, oiled it up. I have good compresion and spark. But it will not run. I can get it to turn over for about 5 seconds after some starter fluid into the carb. I'm thinking its the carb thats the problem. I dont think im getting any gas into the carb. Ive soaked in carb cleaner for an hour.

*My real question is, if the carb is clean and not stuck, should I be able to blow air into it from where the gas line attachs to the carb? I mean the little nipple shaft at the bottom of the carb. Any suggestions would be great.

 

[Joe Reeves]

Re: 1970 Johnson 20hp Carb question

Are you saying that you sank the boat last year and are just getting around to starting it? If so, you have more problems than a obvious fouled carburetor.

If, on the other hand, you got the engine running very soon after getting it out of the water, and ran the engine last year for a period of time...... remove, clean thoroughly, and rebuild that carburetor.

 

[Brianjason6]

Re: 1970 Johnson 20hp Carb question

Take the carb off. Turn it upside down, then blow through the fuel inlet. You shouldn't be able to. Right side up you should be able to easily. If you get any other result the needle and seat is full of junk. Soaking the carb won't clean the needle and seat. Remove them to clean.

 

[mhills]

Re: 1970 Johnson 20hp Carb question

I can get it started for a couple of seconds with some starter fuild sprayed into the carb, but it wont stay running. Thats why I think its the carb (not getting gas), since it will run for a bit. I belive the float is stuck also. Im going to take it apart and clean it out and try it agian. Thanks for the input.

 

[Brianjason6]

Re: 1970 Johnson 20hp Carb question

Kits are cheap and preferable. If the float is sticking it's usually because of the needle and seat being clogged. Sometimes but rarely it's the pin it swings on. Completely tear it down to clean it. On another note..is your fuel pump good? When you are certain the carb is good, check the fuel pump.

 

[mhills]

Re: 1970 Johnson 20hp Carb question

I just tried blowing thru it like you said, and I can when its right side up. Do you think it will work now? I soaked it for a couple of hours tonight in the carb cleaner.

 

[Brianjason6]

Re: 1970 Johnson 20hp Carb question

You must try it upside down also to know it's working. If you can blow through it while it's upside down it's definately faulty or dirty. You now know it opens...but you don't know if it closes. When the float goes up, it stops fuel from entering the bowl. If it's doesn't, your motor floods.

 

[Brianjason6]

Re: 1970 Johnson 20hp Carb question

And STOP using starter fluid. You will ruin your engine. Use mix gas in a spray bottle if you want to spray into the carb.

 

[mhills]

Re: 1970 Johnson 20hp Carb question

Ok, no more starter fluid!! I cannot blow thru it when its upside down, so that means its closing. Now im thinking you are correct and its the fuel pump. How do I go about fixing/cleaning that? Also another note, when the hose is disconnected from the carb and I squeeze the fuel ball, gas comes squriting out.

P.s. I really appreciate all this info!!!!

 

[Brianjason6]

Re: 1970 Johnson 20hp Carb question

Out of what? The line to the carb? It can squirt form there if you keep squeezing. Hook it up to the carb and see if it squirts from the carb while squeezing. It's shouldn't if the float is working. Just like the blow test except right side up. The float should rise and stop the fuel from getting into the carb once full.

 

[Brianjason6]

Re: 1970 Johnson 20hp Carb question

If you don't have any guages to test the fuel pump, and know the carb is perfect, start the engine and slowly pulse the primer bulb. If it keeps running then and stops when you stop, it may be the pump. Pumps are cheap to rebuild if you have the 2inch square one. You must find proper instuctions before attempting. One wrong step and you may destroy an otherwise good fuel pump. If your pump is the 2inch square one, it may have a screw in the center. That screw comes out, then the fuel inlet with a screen comes off. You may want to check that screen for debree.

 

[Brianjason6]

Re: 1970 Johnson 20hp Carb question

Keep in mind I rebuilt and cleaned one carb this week, 4 times before it was perfect. Sometimes once will do, not always.

 

[Joe Reeves]

Re: 1970 Johnson 20hp Carb question

To repeat myself:

Are you saying that you sank the boat last year and are just getting around to starting it? If so, you have more problems than a obvious fouled carburetor.

 

[mhills]

Re: 1970 Johnson 20hp Carb question

When i squeeze the bulb fuel squirts out of the hose that hooks up to the bottom of carb. When i attach carb, it does not and bulb gets hard. checked fuel pump screen and no debris. I took the carb off and tried pull starting it to see how much fuel comes out the hose from the fuel pump. It squrits out a little, is it supposed to squirt out a lot? How much should come out when I do this?

 

[mhills]

Re: 1970 Johnson 20hp Carb question

Just completly cleaned out the carb, looked very clean inside, all ports blown out. needle and float look great. Cannot get it to start up at all now. Maybe bad fuel? Or bad spark. Still trying.

 

[Brianjason6]

Re: 1970 Johnson 20hp Carb question

Just completly cleaned out the carb, looked very clean inside, all ports blown out. needle and float look great. Cannot get it to start up at all now. Maybe bad fuel? Or bad spark. Still trying.

The reason the other fellow is asking if you sank it last year and are just now getting around to it...is this..You may have one or several of these probelms. Rust on the flywheel, rusted points, destoryed coils, ruined rusted plugs, lots of mud or rust in the intake, check vavles destirbed by rust, and the fuel pump would probably be rusted inside too. If you sank it last year, and are just now getting to it, you have a lot more work to do than cleaning the carb.

 

[Brianjason6]

Re: 1970 Johnson 20hp Carb question

Check out the Top Secret File and the top of this forum. It will have the information you need to service the magneto, set the carb properly, and much more.

Here's how you get there. iboats boating forums, repair and maintenance, johnson n evinrude, its at the top of the list.

 

[Joe Reeves]

Re: 1970 Johnson 20hp Carb question

Gone...................

 

[14ftgrumman]

Re: 1970 Johnson 20hp Carb question

Well, answer Joe's question.

How long between sinking the motor and trying to start it?????

Inquiring minds want to know.