1993 75hp Mariner idle trouble

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dazza13130

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Jan 29, 2008
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hi im having trouble with the idle on my rebuilt 75 mariner. I start it up one day and the idle is perfect but if i try it later in the day or even a couple of days later the idle is way to fast. If i adjust the idle screw down abit when its running to fast,then when i start it later it hasnt enough revs to idle.I dont know alot about boat motors but if anyone has any ideas i would be grateful
 
L

Laddies

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Sep 10, 2004
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Re: 1993 75hp Mariner idle trouble

You maybe losing spark on one cyl, have you checked for spark while it's acting up
 
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dazza13130

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Jan 29, 2008
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Re: 1993 75hp Mariner idle trouble

will try that today but it runs smooth when its going and the motor has just been rebuilt and there wasnt a problem before. will let you know how i go,thanks
 
D

dazza13130

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Re: 1993 75hp Mariner idle trouble

Thanks for the advice but i started it up earlier and it was running great on about 800 revs, then started it up a few hours later and it was running on about 2000 revs. it didnt seem to have a miss or running rough both times. i then took a spark plug lead off and it was running terrible. does this mean that the spark is ok? The motor seems to be great once its going, just that uneven idle from one time to the next. any other ideas?
 
R

renny1

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Jul 10, 2007
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Re: 1993 75hp Mariner idle trouble

i know it may not be much help but my car was doing that exact same thing and it was down to some live wire being corroded
 
D

dazza13130

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Jan 29, 2008
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Re: 1993 75hp Mariner idle trouble

hi and thanks. will give anything a go.I will check the wiring out and see if i can find anything, cheers
 
J

jake waller

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Dec 5, 2009
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Re: 1993 75hp Mariner idle trouble

well i know you say u have had it rebilt bit has the head and carbs been refaced beause it can suck air and it can do that thanks jake
 
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