at wits end w Johnson 70hp 1988

sat1962

Petty Officer 2nd Class
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May 26, 2008
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rebuilt carbs and adjusted floats, tipping them up to lean them out....new head gasket.....new exhaust cover gasket.....new fuel lines....new fuel tank.....compression 120-119-121.....spark gap tested....new starter.....new battery.....checked reed valves within manual tolerance....and carbs still load up in throats of carbs.

Please help I've exhausted my thoughts on what it could be. Thanks in advance for help.
 

Theoutdoorsman

Senior Chief Petty Officer
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Mar 6, 2003
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Re: at wits end w Johnson 70hp 1988

Sounds like a float adjustment or needle related issue...... :-/ ..... With the carbs held upside down, the floats should be sitting level with the carb body. Are you certain you didn't damage the needles when adjusting the floats? Excess pressure can render them (needle and seats) permanently damaged. Did you follow Tashasdaddy's frequently asked questions thread when cleaning the carbs?

http://forums.iboats.com/showthread.php?t=244013
 

sat1962

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Re: at wits end w Johnson 70hp 1988

yes i followed the threads on cleaning and rebuilding and i do the test blowing into the fuel entry to see if needle is closing fuel supply it works fine or seems to anything else it could be
 

jtexas

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Re: at wits end w Johnson 70hp 1988

not sure exactly what "load up" means. does it start? idle? push the boat at all?
 

sat1962

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Re: at wits end w Johnson 70hp 1988

not sure exactly what "load up" means. does it start? idle? push the boat at all?

What i mean is carburetors flood gas builds up in throats of them sorry
 

jtexas

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Re: at wits end w Johnson 70hp 1988

If you can prime the fuel line by pumping up the primer bulb until it's firm, and it stays that way for hours, that's evidence of the float valves closing properly.

If can tilt the engine full up far as it will go (engine not running), with the carb bowls full of gas, and see no fuel leaking out of the carb throats, that's further evidence that the float valves are closing properly.

If you can force gas out the carb throats using the primer bulb, that's evidence of leaky float valves.

I didn't see mention of the primer system, is it possible gas is leaking through there?
 

tashasdaddy

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Re: at wits end w Johnson 70hp 1988

as mentioned primer. disconnect the small primer lines each separately, pump the bulb, if you get gas, the primer is leaking flooding the motor. also the red handle has to be in the correct position, inline back over the body of the primer.
 

Dhadley

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Re: at wits end w Johnson 70hp 1988

Ok, gas builds up in the throat of the carb but is the motor still running OK? Does it load up & quit or not accelerate or....what? What does it do that it shouldn't or what does it not do that it should?
 

sat1962

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Re: at wits end w Johnson 70hp 1988

Thanks guys for your suggestions....gonna go look in to it right now.....I'll keep you posted.
 

sat1962

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May 26, 2008
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Re: at wits end w Johnson 70hp 1988

I did the bulb test..stayed hard and no fuel in the carb throat.....tipped engine all the way up....no fuel ran out of the carbs. I have to wait until tomorrow ( it got dark and I didn't want to PO the neighbors) to start it up and test by pulling the primer. Do I have to start the engine to test the primer?

Any other suggestions welcome.......and thank you for the replies and help so far, much appreciated!
 

rickdb1boat

Supreme Mariner
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Jan 23, 2002
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11,195
Re: at wits end w Johnson 70hp 1988

Normal position for the primer is shown in the pic below. Remove the small lines from the primer and pump the bulb. No fuel should squirt out when the lever is in the run position as shown. The engine does not need to be running to do this test..

Carbprimerview2.jpg
 

sat1962

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May 26, 2008
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Re: at wits end w Johnson 70hp 1988

i did all the tests above its not the floats or the primer solenoid so i recleaned carbs .When i started it on muffs it still gets some gas drops on carb throats....... #2 and#3 carb not so much on #1 i noticed it spits out fuel out of the low speed jets at top is this normal Scratchin my head with this thanks for help
 

emdsapmgr

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Re: at wits end w Johnson 70hp 1988

My 1990 60 hp spits fuel out of the top carb. This may be "normal". Seems the engine pumps fuel/oil up to lube the bearing at the top of the engine. The excess comes back through a passage to the intake manifold to the top carb. If you pull the top carb off, you will see the orfice in the intake. When running, it will rythmically spit fuel droplets out the top carb. My engine runs fine, and unless you had the airbox cover off, you would never know what is going on.
 
Joined
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Re: at wits end w Johnson 70hp 1988

Are you sure your not flooding it? I have the same motor 86. Bought new, never had carbs apart. It floods easy.
Only push the key in once or twice to prime, idle lever up-crank it over.

Hope this helps
 
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