older Johnson outboard 7hp doesnt stay running

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older Johnson outboard 7hp doesnt stay running

Postby MAX4Utah » Sat Oct 26, 2013 9:26 pm

I dug an old 1975 Johnson outboard out of the basement. I rebuilt the carb, New fuel lines, New fuel pump gaskets, spark plug and new impeller. It starts up fine but doesn't stay running? It seems to be sucking air or not sealing properly where the fuel line from the tank connects to the motor and just stalls out after about 45 sec. To a minute. Any thought or ideas?
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Re: older Johnson outboard 7hp doesnt stay running

Postby T Man » Sun Oct 27, 2013 1:57 am

You seem to know where the problem is. Motors dontrun right while sucking unmerered air. Fix the vacuum leak and let us know what happens

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Re: older Johnson outboard 7hp doesnt stay running

Postby Boatman » Sun Oct 27, 2013 11:12 am

MAX4Utah wrote:I dug an old 1975 Johnson outboard out of the basement. I rebuilt the carb, New fuel lines, New fuel pump gaskets, spark plug and new impeller. It starts up fine but doesn't stay running? It seems to be sucking air or not sealing properly where the fuel line from the tank connects to the motor and just stalls out after about 45 sec. To a minute. Any thought or ideas?

They didn't make a 7hp in 1975,so what is your model #
If you did a good job on the carb,fuel pump and lines I would look elsewhere. Motor should run for 3-4 min with what fuel is in the carb bowl from when you pumped the carb full with primer bulb. Maybe check Ignition.
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Re: older Johnson outboard 7hp doesnt stay running

Postby MAX4Utah » Sun Oct 27, 2013 12:57 pm

Boatman wrote:
MAX4Utah wrote:I dug an old 1975 Johnson outboard out of the basement. I rebuilt the carb, New fuel lines, New fuel pump gaskets, spark plug and new impeller. It starts up fine but doesn't stay running? It seems to be sucking air or not sealing properly where the fuel line from the tank connects to the motor and just stalls out after about 45 sec. To a minute. Any thought or ideas?

They didn't make a 7hp in 1975,so what is your model #
If you did a good job on the carb,fuel pump and lines I would look elsewhere. Motor should run for 3-4 min with what fuel is in the carb bowl from when you pumped the carb full with primer bulb. Maybe check Ignition.


My bad, its a 6hp...
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Re: older Johnson outboard 7hp doesnt stay running

Postby bassmaster624 » Sun Oct 27, 2013 4:28 pm

check your air valve on your gas tank cap and make sure it is open.
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Re: older Johnson outboard 7hp doesnt stay running

Postby Boatman » Mon Oct 28, 2013 10:18 am

Check the points,under flywheel.
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Re: older Johnson outboard 7hp doesnt stay running

Postby MAX4Utah » Mon Oct 28, 2013 4:41 pm

bassmaster624 wrote:check your air valve on your gas tank cap and make sure it is open.

I checked this one, good to go there.
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Re: older Johnson outboard 7hp doesnt stay running

Postby MAX4Utah » Mon Oct 28, 2013 4:41 pm

Boatman wrote:Check the points,under flywheel.

Would it still be starting ok with this problem?
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Re: older Johnson outboard 7hp doesnt stay running

Postby Boatman » Tue Oct 29, 2013 8:29 am

MAX4Utah wrote:
Boatman wrote:Check the points,under flywheel.

Would it still be starting ok with this problem?


Yea won't run for crap with burnt points! Will throw the timing off also.
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Re: older Johnson outboard 7hp doesnt stay running

Postby Smith » Tue Oct 29, 2013 10:38 am

Will it keep running if you keep pumping the primer bulb? If so, It's probably an air leak at the connector like you suspected. If that's the case, it's most likely just a bad o-ring, although sometimes a new connector is called for.
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