1988 Johnson idle problems

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scottsissy32

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any suggestions when the boat idles it tries to cut off and most of the time it does. changed the plugs, both gas filters, tstats. It runs great when you are cruising, but as soon as you put it in neutral it tries to cut out.???
 
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Haffiman

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Re: 1988 Johnson idle problems

The no 1 sign of a healthy engine is that it idles.
If not, the no 1 test to do is a comp test to check that the engine has a reasonable good balance in the combustion cycles.
More than 10% difference between cylinders and you might be in trouble.
So which engine and what are the comp readings?
 
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scottsissy32

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Re: 1988 Johnson idle problems

Haffiman said:
The no 1 sign of a healthy engine is that it idles.
If not, the no 1 test to do is a comp test to check that the engine has a reasonable good balance in the combustion cycles.
More than 10% difference between cylinders and you might be in trouble.
So which engine and what are the comp readings?[/QUOTE
It is a 115 V4. Havent checked the compression yet? any other suggestions. I was thinking the fuel pump?
Click to expand...
 
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Haffiman

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Re: 1988 Johnson idle problems

That engine is in principle 4 individual engines stacked in a V-shape.
One or more is not working properly - which one?
Fuel pump is common for all of them, probably not.
Test compression, test with a spark-tester that you have spark on all cylinders as a start.
 
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scottsissy32

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Re: 1988 Johnson idle problems

ok i unplugged the oil injector so we can mix our own gas could that cause the fuel pump not to work correctly?
 
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scottsissy32

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Re: 1988 Johnson idle problems

apparently i just found out that the motor used to have an oil tank and the previous owner bypassed it and they just mix oil in with the gas in the tank
 
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Haffiman

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Re: 1988 Johnson idle problems

If it 'runs great when cruising', leave the pump for the time being and concentrate on the basic at the beginning.
 
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scottsissy32

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Re: 1988 Johnson idle problems

also when I turn the idle up it runs great, but when I turn it down thats when it tries to shut off. I am new at this, sorry for all the questions. I checked the compression when I first got it a few months back and it is fine.
 
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scottsissy32

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Re: 1988 Johnson idle problems

cant remember what the compression readings are but the plugs arent fowled out at all? Its very frustrating
 
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Haffiman

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Re: 1988 Johnson idle problems

Another advisor on this board has a sub-text to all his posting:
My questions needs an answer..
'Fine' is not an answer in this, but the real numbers today and not some time back.
Something like going to the doctor saying: I was ok last month, today I'm not. What is wrong????
Post back when you have the numbers and the spark test results.
 
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