Johnson 70 starts but won't continue to run

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griffer73

Recruit
Joined
Jun 21, 2007
Messages
3
I have got a 2000 two stroke 3 cyl outboard that I love. However I now have got a problem. It fires right up every time but will not run longer than about 60-90 seconds and then shuts down as if I pulled the lanyard. Any ideas?
 
licketdsplit756

licketdsplit756

Petty Officer 1st Class
Joined
Jun 15, 2007
Messages
318
Re: Johnson 70 starts but won't continue to run

mine done the same after i launched it ran started right up. then died. i added more gas to the mixure i already had. off i went fishing..i was sure i had the mixture right..but i was wrong..also check make sure your bulb in your fuel line stays tight and that your not just running off the gas you prime the carbs with. this should solve it.
 
G

griffer73

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Joined
Jun 21, 2007
Messages
3
Re: Johnson 70 starts but won't continue to run

Well the bulb stays tight. During the time that it runs I am able to run it at any RPM and this doesn't effect the amt of time it runs. Could be the carbs so I will rebuild and give it a shot. With out repriming the bulb the engine will fire right back up and again run for 60-90 sec. Possible electrical???
 
jtexas

jtexas

Fleet Admiral
Joined
Oct 13, 2003
Messages
8,646
Re: Johnson 70 starts but won't continue to run

welcome to iboats!

What do the plugs look like after it shuts off?
Do a compression test and spark test - set your spark tester gap for 1/2" and look for a sharp blue spark.
 
G

griffer73

Recruit
Joined
Jun 21, 2007
Messages
3
Re: Johnson 70 starts but won't continue to run

Plugs look decent. A little black. Engine seems to be smoking a bit too much?
 
jtexas

jtexas

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Joined
Oct 13, 2003
Messages
8,646
Re: Johnson 70 starts but won't continue to run

"a little black" -- is that wet black or dry black? A light coat of oil after idling is normal, but carbon deposits indicate low combustion temp, maybe a rich mixture. You aren't running NGK plugs are you?
 
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