75 johnson loads up after trolling help

I

i love my johnson

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Help I have a 75 25 hp johnson motor it runs great until you troll with it for a couple of hours then when I go to take of it only runs on the upper cylinder, I have to pull the plug on the lower cylinder and clean it cause it gets rich fouled really bad,also there is like a little oily residue on the powerhead dont know if thats normal or not, could this fouling problem be a bad coil or points? the compression is good I am fustrated with this motor I need something dependable cause I go a ways away on a pretty good sized lake and hate to get stranded should I just get rid of it or is it worth fixing many Thanks.
 
lindy46

lindy46

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Re: 75 johnson loads up after trolling help

Try a hotter spark plug and gap to .035". See if that helps. What plugs are in there now?
 
T

tx1961whaler

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Re: 75 johnson loads up after trolling help

You may also try switching to a full synthetic two-stroke oil.
 
kbait

kbait

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Re: 75 johnson loads up after trolling help

Check spark w/tester to be sure it's as strong on the offending cylinder. I'd personally pop the flywheel, remove both pointsets and file 'em up nice and shiny-new and reinstall/set to .020".
 
I

i love my johnson

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Re: 75 johnson loads up after trolling help

kbait said:
Check spark w/tester to be sure it's as strong on the offending cylinder. I'd personally pop the flywheel, remove both pointsets and file 'em up nice and shiny-new and reinstall/set to .020".
Click to expand...

Thanks a lot as soon as I get time I will try these things its Winter in Wyoming now
 
lindy46

lindy46

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Re: 75 johnson loads up after trolling help

I'd use Champion J6C gapped to .035"
 
jtexas

jtexas

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Re: 75 johnson loads up after trolling help

How long since last carb rebuild? worn float valve can let a little gas seep through, richening the mixture.
 
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steelespike

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Re: 75 johnson loads up after trolling help

If the fuel pump has a pin hole the diaphram it will tend to flood which ever part of the crankcase affects the pump.
I can't remember if upper or lower.
As suggested check that the spark is good.
Carefully adjust the idle mixture screw.Idle speed should be 650.Adjust in gear fully warmed.Get smoothest idle and then turn very slightly toward rich but not enough to affect the idle.
 
I

i love my johnson

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Joined
Dec 10, 2011
Messages
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Re: 75 johnson loads up after trolling help

steelespike said:
If the fuel pump has a pin hole the diaphram it will tend to flood which ever part of the crankcase affects the pump.
I can't remember if upper or lower.
As suggested check that the spark is good.
Carefully adjust the idle mixture screw.Idle speed should be 650.Adjust in gear fully warmed.Get smoothest idle and then turn very slightly toward rich but not enough to affect the idle.
Click to expand...

I didnt know that would effect one cylinder or the other I will bet if I take this old motor and do pretty much the once over like you guys are saying she will probably run like new again I think I will just put a new fuel pump on it rebuild carb use synthetic oil and put new points and even replace both coils bet she will run good then if not I guess I will have to send her to the grave in some deep part of the lake and start over LOL
 
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