1957 18hp johnson starts then dies

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bassman5679

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Feb 23, 2013
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i have a 1957 18 hp johnson outboard. i prime the tank and it starts then dies. it seems like the fuel bowl in carb. is not staying full of fuel. i can prime thetank again and it will start. I noticed fuel running out the front of carb. like the float is sticking open. Help please. Thanks
 
Joe Reeves

Joe Reeves

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Re: 1957 18hp johnson starts then dies

The carburetor requires cleaning and rebuilding.... obvious due to flooding condition. (faulty float, incorrect setting of float, flawed float needle valve, etc).

Pressure tanks need a little time to build up pressure to force fuel to the engine.
 
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82rude

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Re: 1957 18hp johnson starts then dies

be aware that the kit does not have a float and neither do they show one in the float section.
 
kbait

kbait

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Re: 1957 18hp johnson starts then dies

If you get an OMC (now BRP) carb kit, it will include a new float. Sierra aftermarket kits (sold here, napa, etc) don't include floats.

Good luck
 
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bassman5679

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Re: 1957 18hp johnson starts then dies

hi,

I put the rebuild kit in the carb. thee motor starts easy but only runs untill carb runs out of fuel. Prime the tank again andsame thing. If i dont prime the tank or carb.evrytime it wont start. also fuel still runs out of carb. after i prime and choke it. Thanks for you help.
 
nwcove

nwcove

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Re: 1957 18hp johnson starts then dies

will it continue to run if you keep pushing the primer button ?
 
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bassman5679

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Re: 1957 18hp johnson starts then dies

yes it will, it actually ran a little longer after i stop priming.
 
nwcove

nwcove

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Re: 1957 18hp johnson starts then dies

sounds like you may need to reseal the tank as they have to be sealed up tight! ( not sure if it will work with a pressure tank, but you could try setting the tank on a STABLE stand, higher than the carb, just to see if a gravity feed will keep it running.)
 
HighTrim

HighTrim

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Re: 1957 18hp johnson starts then dies

After running, will the tank pssssssssssst (release air) when you crack the cap?

Did you install a new needle/seat with the circlip which attaches to the float arm?
 
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bassman5679

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Re: 1957 18hp johnson starts then dies

the tank does not psssst when cap is loosened. i put new gasket and diaphram on tank. i did put new needle and seat in, but the clip seems really loose on float arm.
 
nwcove

nwcove

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Re: 1957 18hp johnson starts then dies

the needle clip will seem loose, but will pull the needle down when the float drops. as mentioned try to keep the motor running for a few mins by priming it, then check to see if you have "psssst" from the tank when you open the cap. if your not into keeping the motor/tank assembly original, you may want to look into converting to fuel pump. jmo
 
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