Johnson 20hp starts, runs kind of, dies, wont start again

[jwilkey84]

Ok, I posted about this problem about a week ago, and since then I have replaced the impellor, and put in a carb kit. The problem is that I can get the motor to start and run (won't idle very good) but then after it dies or I shut it off, I cant get it to start again. I have checked the spark, it is good. Compression is 105 even when the motor is warm. I did check the fuel bulb after it died, and it was soft. So I kept pumping it while a friend ran the throttle and it seemed to do better. But i disconnected the fuel line on the far side of the fuel pump, and when I pull the rope fuel comes out. Does that mean the fuel pump is ok or not? Also, the motor is getting pretty hot to the touch as well, maybe there is an impellor piece lodges somewhere. Where do I look for that in the most economical fashion? This is all on a 1972 johnson 20 hp motor.

 

[F_R]

Re: Johnson 20hp starts, runs kind of, dies, wont start again

How did you check the spark? That is the most common cause of problems such as you describe.

The fuel pump has absolutely nothing to do with starting the motor. It only takes over after the motor is running. You fill the carburetor with the squeeze bulb, and with that initial fill it should start and run at least till it burns all the gas in the carb, even if you didn't have a fuel pump.

 

[jwilkey84]

Re: Johnson 20hp starts, runs kind of, dies, wont start again

I bought a tester that you put the spark plug wire on the top of and clamp it to the motor, then you adjust the spark gap and attach it to the motor (ground) and pull the rope and watch/listen for spark. It has spark on the first pull as well as after it dies. I wonder why it doesnt idle very good either.?! I thought it was because the carb needed rebuilt, but when I rebuilt it, I couldn't beleive how clean it was already! Also where should I start to look for missing peices of the old impellor? I thought I found most of them when I replaced it, but I suppose ther could be a small chunck up in the water tube or further on in the motor. Should I take the water passage cover off and look in there?

 

[jwilkey84]

Re: Johnson 20hp starts, runs kind of, dies, wont start again

BTW how far should the spark be jumping on this motor. When I tested the spark I probably had the gap adjusted at 1/4 inch. I also read the spark should be white or blue, could someon elaborate on that.

 

[F_R]

Re: Johnson 20hp starts, runs kind of, dies, wont start again

OK, in theory, it should run with that compression, spark, and according to you clean carb. So, now it becomes a guessing game. My advice it to pull the flywheel and take a looksee. Presence of a spark can fool a feller. Don't fret about the spark color.

 

[jwilkey84]

Re: Johnson 20hp starts, runs kind of, dies, wont start again

what exactly am I looking for under the flywheel?

 

[Solittle]

Re: Johnson 20hp starts, runs kind of, dies, wont start again

This "So I kept pumping it while a friend ran the throttle and it seemed to do better." tells me you still have a fuel delivery problem. When you rebuilt the carb exactly what did you do?

 

[jwilkey84]

Re: Johnson 20hp starts, runs kind of, dies, wont start again

I replaced the everything that I could except for the float, which looked fine. I also ensured the float was working properly. I replaced gaskets and all the little round metal thingys ( I have no idea what they are called), I also took off anything that would unscrew and cleaned it all well and put back together. But like I said, it looked very clean to begin with. There wasn't even any trace almounts of varnish in the corners of the bowl or anywhere else. I think I will try to locate the previous owners and see if it was running properly when they last used it in 05.