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1980 johnson possible hydrolock

N

newbreed

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i have a 1980 Johnson 70 seahorse i have been working on. over the weekend we took off the 3 carburetors cleaned and replaced the floats and gaskets. The starter is bad so we have it off and are waiting on the new one to come in so i was pull starting it. it started up pretty quickly and ran what seemed to be good. that was Saturday, on Sunday afternoon i pull started it again, started on 2nd pull no problem. then it sat 4 days, and tonight Thursday i tried to pull start it and when i pulled the rope i almost broke my hand because the thing jammed up. so it slowly turned the wheel by hand and it was jamming up about every 90 deg of turn. so i pulled off the 3 spark plugs. and when i pulled the lower one off fuel poured out big time. so thinking the float was stuck i pulled off the lower carburetor but it seemed okay so i adjusted it a bit put it back on. now with all 3 carburetors back on and the spark plugs out i pulled the wheel with rope and fuel seemed to be spitting out the lower hole where the spark plug goes, not the top 2. maybe still stuff from what was in there i'm not sure....i did put the 3 plugs back in and pull started it pretty easy. I ran, but seemed a bit smokey. Is this problem i had just a carburetor float problem or am i looking at something way more serious?
 
Sounds more like you had a needle and seat problem where the cylinder flooded over from leaving the fuel tank connected.
 
that's what we were thinking, i'm going to check it again today when i get home from work. how would i fix this problem if its still the same thing today? i'm really new with working on outboards. thanks for any help.
 
I had the same thing happen from leaving a portable tank connected to the motor with the vent on the tank closed. When it got hot it built up enough pressure to force the fuel into the cylinder.
 
Update. we took the lower carb off, adjusted the float and checked the needle valve put it back on, and it still was flooding the cylinder with gas, so we took it back off.,put the old needle seat in cause it was working before, and put it back on. also we switched the cap on the gas tank to a vented cap because the one that was on there wasnt vented. everything seems to be working great!! we took it out on the lake yesterday had no problems starting or getting it into gear and going top speed.
 
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