'79 Johnson 70HP sputter

ddtv

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I have a '79 Johnson 70HP. The motors always starts right away, but recently began to sputter if I would open up the throttle. After finished sputtering, she would go fine, but even after running wide open for a bit, she would suddenly begin to sputter and want to die out. I would put it in neutral and try again. Does any one know what is the cause of this?
 

Daviet

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Re: '79 Johnson 60HP sputter

Re: '79 Johnson 60HP sputter

What is your model number, I can't find a 60hp in 1979.
 

ddtv

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Re: '79 Johnson 60HP sputter

Re: '79 Johnson 60HP sputter

Sorry, I had written it was a 60 HP but it's a 70 HP, model 70EL79R
 

Daviet

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Re: '79 Johnson 70HP sputter

You need to start with some basic checks, compression and spark. Spark should jump a 7/16" gap and be bright blue. Are the spark plugs in good shape? If those check out ok, continue on with the fuel delivery system. Check fuel pump pressure and the screen on the pump. It may be time to overhaul the carbs.
 

ddtv

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Re: '79 Johnson 70HP sputter

The fuel pressure is good as well as the fuel filter. I am getting a spark, but I'll put in some new plugs. How do you check the compression?
 

Daviet

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Re: '79 Johnson 70HP sputter

You need a compression tester, check your local auto parts store, sometimes they loan or rent tools.
 
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