1972 johnson starts, runs, but wont start again

[jwilkey84]

I just got a 1972 20hp johnson. I couldnt resist it. It came on a shell lake boat with a good trailer(the tires even hold air) and a 20hp johnson for $20!!! Anyway, I took the carb off and it was really surprisingly clean so I put it back on and took it to the water and it started. There was good water coming out of the exhaust hole and it sounded pretty good, it didnt idle quite as high as I'd like, but it ran. I shut it off, or it died, and then I couldnt get it to start again. good thing it was still hooked to the trailer! So I brought it home for a few days, changed the plugs and tried it again tonigt. Same thing, it ran then I shut it off and now it wont start again. I wonder if it is getting flooded? I know the lean/rich know is one and one half turn out and I don't know what else to do. Please help

 

[HighTrim]

Re: 1972 johnson starts, runs, but wont start again

Good price, if you ever want to sell Ill give you 40 If you pump the primer bulb will it pick up?? Check the spark and compression and let us know what you find.

 

[jwilkey84]

Re: 1972 johnson starts, runs, but wont start again

I felt the primer bulb after it wouldnt start and it was still pretty hard. How would the compression affect this? How do I adequately check the spark, can I just pull the plug out of the cylinder and watch for spark or do I need to measure it some how?

 

[freddyray21]

Re: 1972 johnson starts, runs, but wont start again

you can buy a cheap spark tester at an auto parts store. Hook one end to ground and the other to the spark plug lead. You should see a good blue spark jump 1/4 to 3/8 or an inch I would quess. The coils maybe going bad. Often when they are once they get warm they fail causing no spark. Take it out and when it dies and won't start again check the spark and see if you have any. If you don't I would think to replace the coils.

 

[freddyray21]

Re: 1972 johnson starts, runs, but wont start again

btw High Trim I'll see your 20 and raise you 20

 

[tashasdaddy]

Re: 1972 johnson starts, runs, but wont start again

i suggest you read awakening a sleeping outboard in the faq section. then outboard won't start. report results.

 

[jwilkey84]

Re: 1972 johnson starts, runs, but wont start again

ok guys, I took it out again tonight and started it. It started on the first pull. I let it run for probably 2 minutes, then I let it die, since it doesn't idle very well at the moment. Then I put on my new spark plug wire tester and I have a good 3/8" spark on both wires. But the motor will not start up again. Also the throttle response seems slow, and it isnt a slow linkage situation because I am running the throttle with my finger right on the carb. So I know it's not the power packs or whatever supplies spark, but I am still looking for answers. Maybe it is a carb problem?

 

[Benny1963]

Re: 1972 johnson starts, runs, but wont start again

running with your figer at carbs is not allowing the timing to come into play
try shooting some pre mix into carb see if she starts may need to build
carb once you get it running youse throttle to rev it up not just link at carb
if you can get it idleing then you can run mix screw in it should pick up idle
run in till it wants to die then back out slowly until it reaches its highest point
then go 1/8 further out . once you get to that point put it in the water and adjust your idle speed.
bennyb

 

[jwilkey84]

Re: 1972 johnson starts, runs, but wont start again

so you think it isn't getting fuel to start again? When I try to start it the second time, I even pull the choke out. As for the finger operation of the carb, I am just moving the same rod that the throttle does.

 

[Benny1963]

Re: 1972 johnson starts, runs, but wont start again

i see abut the rod ,
i know that if you have fire .at plugs and gas at carbs it should start
try priming it by spraying it with premix when this happens ,if it starts rigt up you have a fuel deliv prob. or carb prob.
post back after you test
benny b

 

[freddyray21]

Re: 1972 johnson starts, runs, but wont start again

when it dies and will not restart are you pumping the primer bulb again? It may very well be that priming it is filling the float bowl and a weak or non functioning fuel pump maybe not filling it up as it runs. They will run a couple of minutes on the fuel in the bowl. Try priming it again after it starts to fill the float bowl again. If there is no fuel in the bowl all the choking in the world won't get fuel to the motor. Check all the gas lines for cracks or leaks also. Air getting sucked in will inhibit gas flow to the carb.

 

[jwilkey84]

Re: 1972 johnson starts, runs, but wont start again

after it dies, there is still plenty of pressure at the hand pump.

 

[bgbass.1]

Re: 1972 johnson starts, runs, but wont start again

buy a carb. rebuild kit and it should run great i had one for many years never had a problem