1980 15hp johnson stalling out, need help please

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bodman374

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Sep 21, 2011
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My 1980 15 hp johnson is boggin down then stalling at 3/4 to full throttle. Its runs at idle/ trolling speeds fine but will run at full for 5 min and cut out sometimes it runs for a while then cuts out, its intermittant and i cant figure out why. Ive cleaned the carbeurator multiple times its got a new fuel filter and pump, theres no leaks that i can see, i replaced the fittings on the fuel line, the ball seems to hold pressure when not in use , it has a new tank, ive tried adjusting the lean/rich adjustment, it seems like i tried everything. Anybody have any ideas?
 
oldcatamount

oldcatamount

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Re: 1980 15hp johnson stalling out, need help please

Is it running hot? Check the pee stream next time you're running the motor. When the motor is at idle, you should be able to touch the head and hold your finger on it for a second or two without being burned, If the impeller is bad, the motor will heat up and squeeze the pistons which will shut it down.
 
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dazk14

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Jul 22, 2008
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Re: 1980 15hp johnson stalling out, need help please

oldcatamount said:
Is it running hot? Check the pee stream next time you're running the motor. When the motor is at idle, you should be able to touch the head and hold your finger on it for a second or two without being burned, If the impeller is bad, the motor will heat up and squeeze the pistons which will shut it down.
Click to expand...

Add to that, defective or clogged thermo will produce same.
 
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bodman374

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Sep 21, 2011
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Re: 1980 15hp johnson stalling out, need help please

dazk14 said:
Add to that, defective or clogged thermo will produce same.
Click to expand...

The stream is solid, its looks fine, maybe the thermostat is letting water by too fast and not sucking enough heat out, ill run it and see how hot it is, thanks for the tip
 
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OptsyEagle

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Re: 1980 15hp johnson stalling out, need help please

When it cuts out does it seem to want to stall or does it simply bog down, then surge and then bog down again, etc. For the first issue you never mentioned if you tried squeezing the primer bulb when it does this and any effect it might of had. The second issue would most likely be ignition related with either your wire connections, powerpack or a coil giving you an intermittent spark on one cylinder.
 
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bodman374

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Sep 21, 2011
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Re: 1980 15hp johnson stalling out, need help please

OptsyEagle said:
When it cuts out does it seem to want to stall or does it simply bog down, then surge and then bog down again, etc. For the first issue you never mentioned if you tried squeezing the primer bulb when it does this and any effect it might of had. The second issue would most likely be ignition related with either your wire connections, powerpack or a coil giving you an intermittent spark on one cylinder.
Click to expand...

i did try squeezing the bulb and it didnt help, it doesnt die out then throttle up it just dies and thats it. sometimes it starts right up, one time i had to get towed in but it started up when i got it back home
 
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